up follow livre

venv/lib/python3.13/site-packages/scipy/optimize/__init__.pxd

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+from .optimize cimport cython_optimize

venv/lib/python3.13/site-packages/scipy/optimize/__init__.py

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+"""
+=====================================================
+Optimization and root finding (:mod:`scipy.optimize`)
+=====================================================
+
+.. currentmodule:: scipy.optimize
+
+.. toctree::
+   :hidden:
+
+   optimize.cython_optimize
+
+SciPy ``optimize`` provides functions for minimizing (or maximizing)
+objective functions, possibly subject to constraints. It includes
+solvers for nonlinear problems (with support for both local and global
+optimization algorithms), linear programming, constrained
+and nonlinear least-squares, root finding, and curve fitting.
+
+Common functions and objects, shared across different solvers, are:
+
+.. autosummary::
+   :toctree: generated/
+
+   show_options - Show specific options optimization solvers.
+   OptimizeResult - The optimization result returned by some optimizers.
+   OptimizeWarning - The optimization encountered problems.
+
+
+Optimization
+============
+
+Scalar functions optimization
+-----------------------------
+
+.. autosummary::
+   :toctree: generated/
+
+   minimize_scalar - Interface for minimizers of univariate functions
+
+The `minimize_scalar` function supports the following methods:
+
+.. toctree::
+
+   optimize.minimize_scalar-brent
+   optimize.minimize_scalar-bounded
+   optimize.minimize_scalar-golden
+
+Local (multivariate) optimization
+---------------------------------
+
+.. autosummary::
+   :toctree: generated/
+
+   minimize - Interface for minimizers of multivariate functions.
+
+The `minimize` function supports the following methods:
+
+.. toctree::
+
+   optimize.minimize-neldermead
+   optimize.minimize-powell
+   optimize.minimize-cg
+   optimize.minimize-bfgs
+   optimize.minimize-newtoncg
+   optimize.minimize-lbfgsb
+   optimize.minimize-tnc
+   optimize.minimize-cobyla
+   optimize.minimize-cobyqa
+   optimize.minimize-slsqp
+   optimize.minimize-trustconstr
+   optimize.minimize-dogleg
+   optimize.minimize-trustncg
+   optimize.minimize-trustkrylov
+   optimize.minimize-trustexact
+
+Constraints are passed to `minimize` function as a single object or
+as a list of objects from the following classes:
+
+.. autosummary::
+   :toctree: generated/
+
+   NonlinearConstraint - Class defining general nonlinear constraints.
+   LinearConstraint - Class defining general linear constraints.
+
+Simple bound constraints are handled separately and there is a special class
+for them:
+
+.. autosummary::
+   :toctree: generated/
+
+   Bounds - Bound constraints.
+
+Quasi-Newton strategies implementing `HessianUpdateStrategy`
+interface can be used to approximate the Hessian in `minimize`
+function (available only for the 'trust-constr' method). Available
+quasi-Newton methods implementing this interface are:
+
+.. autosummary::
+   :toctree: generated/
+
+   BFGS - Broyden-Fletcher-Goldfarb-Shanno (BFGS) Hessian update strategy.
+   SR1 - Symmetric-rank-1 Hessian update strategy.
+
+.. _global_optimization:
+
+Global optimization
+-------------------
+
+.. autosummary::
+   :toctree: generated/
+
+   basinhopping - Basinhopping stochastic optimizer.
+   brute - Brute force searching optimizer.
+   differential_evolution - Stochastic optimizer using differential evolution.
+
+   shgo - Simplicial homology global optimizer.
+   dual_annealing - Dual annealing stochastic optimizer.
+   direct - DIRECT (Dividing Rectangles) optimizer.
+
+Least-squares and curve fitting
+===============================
+
+Nonlinear least-squares
+-----------------------
+
+.. autosummary::
+   :toctree: generated/
+
+   least_squares - Solve a nonlinear least-squares problem with bounds on the variables.
+
+Linear least-squares
+--------------------
+
+.. autosummary::
+   :toctree: generated/
+
+   nnls - Linear least-squares problem with non-negativity constraint.
+   lsq_linear - Linear least-squares problem with bound constraints.
+   isotonic_regression - Least squares problem of isotonic regression via PAVA.
+
+Curve fitting
+-------------
+
+.. autosummary::
+   :toctree: generated/
+
+   curve_fit -- Fit curve to a set of points.
+
+Root finding
+============
+
+Scalar functions
+----------------
+.. autosummary::
+   :toctree: generated/
+
+   root_scalar - Unified interface for nonlinear solvers of scalar functions.
+   brentq - quadratic interpolation Brent method.
+   brenth - Brent method, modified by Harris with hyperbolic extrapolation.
+   ridder - Ridder's method.
+   bisect - Bisection method.
+   newton - Newton's method (also Secant and Halley's methods).
+   toms748 - Alefeld, Potra & Shi Algorithm 748.
+   RootResults - The root finding result returned by some root finders.
+
+The `root_scalar` function supports the following methods:
+
+.. toctree::
+
+   optimize.root_scalar-brentq
+   optimize.root_scalar-brenth
+   optimize.root_scalar-bisect
+   optimize.root_scalar-ridder
+   optimize.root_scalar-newton
+   optimize.root_scalar-toms748
+   optimize.root_scalar-secant
+   optimize.root_scalar-halley
+
+
+
+The table below lists situations and appropriate methods, along with
+*asymptotic* convergence rates per iteration (and per function evaluation)
+for successful convergence to a simple root(*).
+Bisection is the slowest of them all, adding one bit of accuracy for each
+function evaluation, but is guaranteed to converge.
+The other bracketing methods all (eventually) increase the number of accurate
+bits by about 50% for every function evaluation.
+The derivative-based methods, all built on `newton`, can converge quite quickly
+if the initial value is close to the root.  They can also be applied to
+functions defined on (a subset of) the complex plane.
+
++-------------+----------+----------+-----------+-------------+-------------+----------------+
+| Domain of f | Bracket? |    Derivatives?      | Solvers     |        Convergence           |
++             +          +----------+-----------+             +-------------+----------------+
+|             |          | `fprime` | `fprime2` |             | Guaranteed? |  Rate(s)(*)    |
++=============+==========+==========+===========+=============+=============+================+
+| `R`         | Yes      | N/A      | N/A       | - bisection | - Yes       | - 1 "Linear"   |
+|             |          |          |           | - brentq    | - Yes       | - >=1, <= 1.62 |
+|             |          |          |           | - brenth    | - Yes       | - >=1, <= 1.62 |
+|             |          |          |           | - ridder    | - Yes       | - 2.0 (1.41)   |
+|             |          |          |           | - toms748   | - Yes       | - 2.7 (1.65)   |
++-------------+----------+----------+-----------+-------------+-------------+----------------+
+| `R` or `C`  | No       | No       | No        | secant      | No          | 1.62 (1.62)    |
++-------------+----------+----------+-----------+-------------+-------------+----------------+
+| `R` or `C`  | No       | Yes      | No        | newton      | No          | 2.00 (1.41)    |
++-------------+----------+----------+-----------+-------------+-------------+----------------+
+| `R` or `C`  | No       | Yes      | Yes       | halley      | No          | 3.00 (1.44)    |
++-------------+----------+----------+-----------+-------------+-------------+----------------+
+
+.. seealso::
+
+   `scipy.optimize.cython_optimize` -- Typed Cython versions of root finding functions
+
+Fixed point finding:
+
+.. autosummary::
+   :toctree: generated/
+
+   fixed_point - Single-variable fixed-point solver.
+
+Multidimensional
+----------------
+
+.. autosummary::
+   :toctree: generated/
+
+   root - Unified interface for nonlinear solvers of multivariate functions.
+
+The `root` function supports the following methods:
+
+.. toctree::
+
+   optimize.root-hybr
+   optimize.root-lm
+   optimize.root-broyden1
+   optimize.root-broyden2
+   optimize.root-anderson
+   optimize.root-linearmixing
+   optimize.root-diagbroyden
+   optimize.root-excitingmixing
+   optimize.root-krylov
+   optimize.root-dfsane
+   
+Elementwise Minimization and Root Finding
+=========================================
+
+.. toctree::
+   :maxdepth: 3
+
+   optimize.elementwise
+
+Linear programming / MILP
+=========================
+
+.. autosummary::
+   :toctree: generated/
+
+   milp -- Mixed integer linear programming.
+   linprog -- Unified interface for minimizers of linear programming problems.
+
+The `linprog` function supports the following methods:
+
+.. toctree::
+
+   optimize.linprog-simplex
+   optimize.linprog-interior-point
+   optimize.linprog-revised_simplex
+   optimize.linprog-highs-ipm
+   optimize.linprog-highs-ds
+   optimize.linprog-highs
+
+The simplex, interior-point, and revised simplex methods support callback
+functions, such as:
+
+.. autosummary::
+   :toctree: generated/
+
+   linprog_verbose_callback -- Sample callback function for linprog (simplex).
+
+Assignment problems
+===================
+
+.. autosummary::
+   :toctree: generated/
+
+   linear_sum_assignment -- Solves the linear-sum assignment problem.
+   quadratic_assignment -- Solves the quadratic assignment problem.
+
+The `quadratic_assignment` function supports the following methods:
+
+.. toctree::
+
+   optimize.qap-faq
+   optimize.qap-2opt
+
+Utilities
+=========
+
+Finite-difference approximation
+-------------------------------
+
+.. autosummary::
+   :toctree: generated/
+
+   approx_fprime - Approximate the gradient of a scalar function.
+   check_grad - Check the supplied derivative using finite differences.
+
+
+Line search
+-----------
+
+.. autosummary::
+   :toctree: generated/
+
+   bracket - Bracket a minimum, given two starting points.
+   line_search - Return a step that satisfies the strong Wolfe conditions.
+
+Hessian approximation
+---------------------
+
+.. autosummary::
+   :toctree: generated/
+
+   LbfgsInvHessProduct - Linear operator for L-BFGS approximate inverse Hessian.
+   HessianUpdateStrategy - Interface for implementing Hessian update strategies
+
+Benchmark problems
+------------------
+
+.. autosummary::
+   :toctree: generated/
+
+   rosen - The Rosenbrock function.
+   rosen_der - The derivative of the Rosenbrock function.
+   rosen_hess - The Hessian matrix of the Rosenbrock function.
+   rosen_hess_prod - Product of the Rosenbrock Hessian with a vector.
+
+Legacy functions
+================
+
+The functions below are not recommended for use in new scripts;
+all of these methods are accessible via a newer, more consistent
+interfaces, provided by the interfaces above.
+
+Optimization
+------------
+
+General-purpose multivariate methods:
+
+.. autosummary::
+   :toctree: generated/
+
+   fmin - Nelder-Mead Simplex algorithm.
+   fmin_powell - Powell's (modified) conjugate direction method.
+   fmin_cg - Non-linear (Polak-Ribiere) conjugate gradient algorithm.
+   fmin_bfgs - Quasi-Newton method (Broydon-Fletcher-Goldfarb-Shanno).
+   fmin_ncg - Line-search Newton Conjugate Gradient.
+
+Constrained multivariate methods:
+
+.. autosummary::
+   :toctree: generated/
+
+   fmin_l_bfgs_b - Zhu, Byrd, and Nocedal's constrained optimizer.
+   fmin_tnc - Truncated Newton code.
+   fmin_cobyla - Constrained optimization by linear approximation.
+   fmin_slsqp - Minimization using sequential least-squares programming.
+
+Univariate (scalar) minimization methods:
+
+.. autosummary::
+   :toctree: generated/
+
+   fminbound - Bounded minimization of a scalar function.
+   brent - 1-D function minimization using Brent method.
+   golden - 1-D function minimization using Golden Section method.
+
+Least-squares
+-------------
+
+.. autosummary::
+   :toctree: generated/
+
+   leastsq - Minimize the sum of squares of M equations in N unknowns.
+
+Root finding
+------------
+
+General nonlinear solvers:
+
+.. autosummary::
+   :toctree: generated/
+
+   fsolve - Non-linear multivariable equation solver.
+   broyden1 - Broyden's first method.
+   broyden2 - Broyden's second method.
+   NoConvergence -  Exception raised when nonlinear solver does not converge.
+
+Large-scale nonlinear solvers:
+
+.. autosummary::
+   :toctree: generated/
+
+   newton_krylov
+   anderson
+
+   BroydenFirst
+   InverseJacobian
+   KrylovJacobian
+
+Simple iteration solvers:
+
+.. autosummary::
+   :toctree: generated/
+
+   excitingmixing
+   linearmixing
+   diagbroyden
+
+"""  # noqa: E501
+
+from ._optimize import *
+from ._minimize import *
+from ._root import *
+from ._root_scalar import *
+from ._minpack_py import *
+from ._zeros_py import *
+from ._lbfgsb_py import fmin_l_bfgs_b, LbfgsInvHessProduct
+from ._tnc import fmin_tnc
+from ._cobyla_py import fmin_cobyla
+from ._nonlin import *
+from ._slsqp_py import fmin_slsqp
+from ._nnls import nnls
+from ._basinhopping import basinhopping
+from ._linprog import linprog, linprog_verbose_callback
+from ._lsap import linear_sum_assignment
+from ._differentialevolution import differential_evolution
+from ._lsq import least_squares, lsq_linear
+from ._isotonic import isotonic_regression
+from ._constraints import (NonlinearConstraint,
+                           LinearConstraint,
+                           Bounds)
+from ._hessian_update_strategy import HessianUpdateStrategy, BFGS, SR1
+from ._shgo import shgo
+from ._dual_annealing import dual_annealing
+from ._qap import quadratic_assignment
+from ._direct_py import direct
+from ._milp import milp
+
+# Deprecated namespaces, to be removed in v2.0.0
+from . import (
+    cobyla, lbfgsb, linesearch, minpack, minpack2, moduleTNC, nonlin, optimize,
+    slsqp, tnc, zeros
+)
+
+__all__ = [s for s in dir() if not s.startswith('_')]
+
+from scipy._lib._testutils import PytestTester
+test = PytestTester(__name__)
+del PytestTester

venv/lib/python3.13/site-packages/scipy/optimize/_basinhopping.py

@@ -0,0 +1,741 @@
+"""
+basinhopping: The basinhopping global optimization algorithm
+"""
+import numpy as np
+import math
+import inspect
+import scipy.optimize
+from scipy._lib._util import check_random_state, _transition_to_rng
+
+__all__ = ['basinhopping']
+
+
+_params = (inspect.Parameter('res_new', kind=inspect.Parameter.KEYWORD_ONLY),
+           inspect.Parameter('res_old', kind=inspect.Parameter.KEYWORD_ONLY))
+_new_accept_test_signature = inspect.Signature(parameters=_params)
+
+
+class Storage:
+    """
+    Class used to store the lowest energy structure
+    """
+    def __init__(self, minres):
+        self._add(minres)
+
+    def _add(self, minres):
+        self.minres = minres
+        self.minres.x = np.copy(minres.x)
+
+    def update(self, minres):
+        if minres.success and (minres.fun < self.minres.fun
+                               or not self.minres.success):
+            self._add(minres)
+            return True
+        else:
+            return False
+
+    def get_lowest(self):
+        return self.minres
+
+
+class BasinHoppingRunner:
+    """This class implements the core of the basinhopping algorithm.
+
+    x0 : ndarray
+        The starting coordinates.
+    minimizer : callable
+        The local minimizer, with signature ``result = minimizer(x)``.
+        The return value is an `optimize.OptimizeResult` object.
+    step_taking : callable
+        This function displaces the coordinates randomly. Signature should
+        be ``x_new = step_taking(x)``. Note that `x` may be modified in-place.
+    accept_tests : list of callables
+        Each test is passed the kwargs `f_new`, `x_new`, `f_old` and
+        `x_old`. These tests will be used to judge whether or not to accept
+        the step. The acceptable return values are True, False, or ``"force
+        accept"``. If any of the tests return False then the step is rejected.
+        If ``"force accept"``, then this will override any other tests in
+        order to accept the step. This can be used, for example, to forcefully
+        escape from a local minimum that ``basinhopping`` is trapped in.
+    disp : bool, optional
+        Display status messages.
+
+    """
+    def __init__(self, x0, minimizer, step_taking, accept_tests, disp=False):
+        self.x = np.copy(x0)
+        self.minimizer = minimizer
+        self.step_taking = step_taking
+        self.accept_tests = accept_tests
+        self.disp = disp
+
+        self.nstep = 0
+
+        # initialize return object
+        self.res = scipy.optimize.OptimizeResult()
+        self.res.minimization_failures = 0
+
+        # do initial minimization
+        minres = minimizer(self.x)
+        if not minres.success:
+            self.res.minimization_failures += 1
+            if self.disp:
+                print("warning: basinhopping: local minimization failure")
+        self.x = np.copy(minres.x)
+        self.energy = minres.fun
+        self.incumbent_minres = minres  # best minimize result found so far
+        if self.disp:
+            print(f"basinhopping step {self.nstep}: f {self.energy:g}")
+
+        # initialize storage class
+        self.storage = Storage(minres)
+
+        if hasattr(minres, "nfev"):
+            self.res.nfev = minres.nfev
+        if hasattr(minres, "njev"):
+            self.res.njev = minres.njev
+        if hasattr(minres, "nhev"):
+            self.res.nhev = minres.nhev
+
+    def _monte_carlo_step(self):
+        """Do one Monte Carlo iteration
+
+        Randomly displace the coordinates, minimize, and decide whether
+        or not to accept the new coordinates.
+        """
+        # Take a random step.  Make a copy of x because the step_taking
+        # algorithm might change x in place
+        x_after_step = np.copy(self.x)
+        x_after_step = self.step_taking(x_after_step)
+
+        # do a local minimization
+        minres = self.minimizer(x_after_step)
+        x_after_quench = minres.x
+        energy_after_quench = minres.fun
+        if not minres.success:
+            self.res.minimization_failures += 1
+            if self.disp:
+                print("warning: basinhopping: local minimization failure")
+        if hasattr(minres, "nfev"):
+            self.res.nfev += minres.nfev
+        if hasattr(minres, "njev"):
+            self.res.njev += minres.njev
+        if hasattr(minres, "nhev"):
+            self.res.nhev += minres.nhev
+
+        # accept the move based on self.accept_tests. If any test is False,
+        # then reject the step.  If any test returns the special string
+        # 'force accept', then accept the step regardless. This can be used
+        # to forcefully escape from a local minimum if normal basin hopping
+        # steps are not sufficient.
+        accept = True
+        for test in self.accept_tests:
+            if inspect.signature(test) == _new_accept_test_signature:
+                testres = test(res_new=minres, res_old=self.incumbent_minres)
+            else:
+                testres = test(f_new=energy_after_quench, x_new=x_after_quench,
+                               f_old=self.energy, x_old=self.x)
+
+            if testres == 'force accept':
+                accept = True
+                break
+            elif testres is None:
+                raise ValueError("accept_tests must return True, False, or "
+                                 "'force accept'")
+            elif not testres:
+                accept = False
+
+        # Report the result of the acceptance test to the take step class.
+        # This is for adaptive step taking
+        if hasattr(self.step_taking, "report"):
+            self.step_taking.report(accept, f_new=energy_after_quench,
+                                    x_new=x_after_quench, f_old=self.energy,
+                                    x_old=self.x)
+
+        return accept, minres
+
+    def one_cycle(self):
+        """Do one cycle of the basinhopping algorithm
+        """
+        self.nstep += 1
+        new_global_min = False
+
+        accept, minres = self._monte_carlo_step()
+
+        if accept:
+            self.energy = minres.fun
+            self.x = np.copy(minres.x)
+            self.incumbent_minres = minres  # best minimize result found so far
+            new_global_min = self.storage.update(minres)
+
+        # print some information
+        if self.disp:
+            self.print_report(minres.fun, accept)
+            if new_global_min:
+                print(
+                    f"found new global minimum on step {self.nstep} with "
+                    f"function value {self.energy:g}"
+                )
+
+        # save some variables as BasinHoppingRunner attributes
+        self.xtrial = minres.x
+        self.energy_trial = minres.fun
+        self.accept = accept
+
+        return new_global_min
+
+    def print_report(self, energy_trial, accept):
+        """print a status update"""
+        minres = self.storage.get_lowest()
+        print(
+            f"basinhopping step {self.nstep}: f {self.energy:g} "
+            f"trial_f {energy_trial:g} accepted {accept} "
+            f"lowest_f {minres.fun:g}"
+        )
+
+
+class AdaptiveStepsize:
+    """
+    Class to implement adaptive stepsize.
+
+    This class wraps the step taking class and modifies the stepsize to
+    ensure the true acceptance rate is as close as possible to the target.
+
+    Parameters
+    ----------
+    takestep : callable
+        The step taking routine.  Must contain modifiable attribute
+        takestep.stepsize
+    accept_rate : float, optional
+        The target step acceptance rate
+    interval : int, optional
+        Interval for how often to update the stepsize
+    factor : float, optional
+        The step size is multiplied or divided by this factor upon each
+        update.
+    verbose : bool, optional
+        Print information about each update
+
+    """
+    def __init__(self, takestep, accept_rate=0.5, interval=50, factor=0.9,
+                 verbose=True):
+        self.takestep = takestep
+        self.target_accept_rate = accept_rate
+        self.interval = interval
+        self.factor = factor
+        self.verbose = verbose
+
+        self.nstep = 0
+        self.nstep_tot = 0
+        self.naccept = 0
+
+    def __call__(self, x):
+        return self.take_step(x)
+
+    def _adjust_step_size(self):
+        old_stepsize = self.takestep.stepsize
+        accept_rate = float(self.naccept) / self.nstep
+        if accept_rate > self.target_accept_rate:
+            # We're accepting too many steps. This generally means we're
+            # trapped in a basin. Take bigger steps.
+            self.takestep.stepsize /= self.factor
+        else:
+            # We're not accepting enough steps. Take smaller steps.
+            self.takestep.stepsize *= self.factor
+        if self.verbose:
+            print(f"adaptive stepsize: acceptance rate {accept_rate:f} target "
+                  f"{self.target_accept_rate:f} new stepsize "
+                  f"{self.takestep.stepsize:g} old stepsize {old_stepsize:g}")
+
+    def take_step(self, x):
+        self.nstep += 1
+        self.nstep_tot += 1
+        if self.nstep % self.interval == 0:
+            self._adjust_step_size()
+        return self.takestep(x)
+
+    def report(self, accept, **kwargs):
+        "called by basinhopping to report the result of the step"
+        if accept:
+            self.naccept += 1
+
+
+class RandomDisplacement:
+    """Add a random displacement of maximum size `stepsize` to each coordinate.
+
+    Calling this updates `x` in-place.
+
+    Parameters
+    ----------
+    stepsize : float, optional
+        Maximum stepsize in any dimension
+    rng : {None, int, `numpy.random.Generator`}, optional
+        Random number generator
+    """
+
+    def __init__(self, stepsize=0.5, rng=None):
+        self.stepsize = stepsize
+        self.rng = check_random_state(rng)
+
+    def __call__(self, x):
+        x += self.rng.uniform(-self.stepsize, self.stepsize,
+                              np.shape(x))
+        return x
+
+
+class MinimizerWrapper:
+    """
+    wrap a minimizer function as a minimizer class
+    """
+    def __init__(self, minimizer, func=None, **kwargs):
+        self.minimizer = minimizer
+        self.func = func
+        self.kwargs = kwargs
+
+    def __call__(self, x0):
+        if self.func is None:
+            return self.minimizer(x0, **self.kwargs)
+        else:
+            return self.minimizer(self.func, x0, **self.kwargs)
+
+
+class Metropolis:
+    """Metropolis acceptance criterion.
+
+    Parameters
+    ----------
+    T : float
+        The "temperature" parameter for the accept or reject criterion.
+    rng : {None, int, `numpy.random.Generator`}, optional
+        Random number generator used for acceptance test.
+
+    """
+
+    def __init__(self, T, rng=None):
+        # Avoid ZeroDivisionError since "MBH can be regarded as a special case
+        # of the BH framework with the Metropolis criterion, where temperature
+        # T = 0." (Reject all steps that increase energy.)
+        self.beta = 1.0 / T if T != 0 else float('inf')
+        self.rng = check_random_state(rng)
+
+    def accept_reject(self, res_new, res_old):
+        """
+        Assuming the local search underlying res_new was successful:
+        If new energy is lower than old, it will always be accepted.
+        If new is higher than old, there is a chance it will be accepted,
+        less likely for larger differences.
+        """
+        with np.errstate(invalid='ignore'):
+            # The energy values being fed to Metropolis are 1-length arrays, and if
+            # they are equal, their difference is 0, which gets multiplied by beta,
+            # which is inf, and array([0]) * float('inf') causes
+            #
+            # RuntimeWarning: invalid value encountered in multiply
+            #
+            # Ignore this warning so when the algorithm is on a flat plane, it always
+            # accepts the step, to try to move off the plane.
+            prod = -(res_new.fun - res_old.fun) * self.beta
+            w = math.exp(min(0, prod))
+
+        rand = self.rng.uniform()
+        return w >= rand and (res_new.success or not res_old.success)
+
+    def __call__(self, *, res_new, res_old):
+        """
+        f_new and f_old are mandatory in kwargs
+        """
+        return bool(self.accept_reject(res_new, res_old))
+
+
+@_transition_to_rng("seed", position_num=12, replace_doc=True)
+def basinhopping(func, x0, niter=100, T=1.0, stepsize=0.5,
+                 minimizer_kwargs=None, take_step=None, accept_test=None,
+                 callback=None, interval=50, disp=False, niter_success=None,
+                 rng=None, *, target_accept_rate=0.5, stepwise_factor=0.9):
+    """Find the global minimum of a function using the basin-hopping algorithm.
+
+    Basin-hopping is a two-phase method that combines a global stepping
+    algorithm with local minimization at each step. Designed to mimic
+    the natural process of energy minimization of clusters of atoms, it works
+    well for similar problems with "funnel-like, but rugged" energy landscapes
+    [5]_.
+
+    As the step-taking, step acceptance, and minimization methods are all
+    customizable, this function can also be used to implement other two-phase
+    methods.
+
+    Parameters
+    ----------
+    func : callable ``f(x, *args)``
+        Function to be optimized.  ``args`` can be passed as an optional item
+        in the dict `minimizer_kwargs`
+    x0 : array_like
+        Initial guess.
+    niter : integer, optional
+        The number of basin-hopping iterations. There will be a total of
+        ``niter + 1`` runs of the local minimizer.
+    T : float, optional
+        The "temperature" parameter for the acceptance or rejection criterion.
+        Higher "temperatures" mean that larger jumps in function value will be
+        accepted.  For best results `T` should be comparable to the
+        separation (in function value) between local minima.
+    stepsize : float, optional
+        Maximum step size for use in the random displacement.
+    minimizer_kwargs : dict, optional
+        Extra keyword arguments to be passed to the local minimizer
+        `scipy.optimize.minimize` Some important options could be:
+
+        method : str
+            The minimization method (e.g. ``"L-BFGS-B"``)
+        args : tuple
+            Extra arguments passed to the objective function (`func`) and
+            its derivatives (Jacobian, Hessian).
+
+    take_step : callable ``take_step(x)``, optional
+        Replace the default step-taking routine with this routine. The default
+        step-taking routine is a random displacement of the coordinates, but
+        other step-taking algorithms may be better for some systems.
+        `take_step` can optionally have the attribute ``take_step.stepsize``.
+        If this attribute exists, then `basinhopping` will adjust
+        ``take_step.stepsize`` in order to try to optimize the global minimum
+        search.
+    accept_test : callable, ``accept_test(f_new=f_new, x_new=x_new, f_old=fold, x_old=x_old)``, optional
+        Define a test which will be used to judge whether to accept the
+        step. This will be used in addition to the Metropolis test based on
+        "temperature" `T`. The acceptable return values are True,
+        False, or ``"force accept"``. If any of the tests return False
+        then the step is rejected. If the latter, then this will override any
+        other tests in order to accept the step. This can be used, for example,
+        to forcefully escape from a local minimum that `basinhopping` is
+        trapped in.
+    callback : callable, ``callback(x, f, accept)``, optional
+        A callback function which will be called for all minima found. ``x``
+        and ``f`` are the coordinates and function value of the trial minimum,
+        and ``accept`` is whether that minimum was accepted. This can
+        be used, for example, to save the lowest N minima found. Also,
+        `callback` can be used to specify a user defined stop criterion by
+        optionally returning True to stop the `basinhopping` routine.
+    interval : integer, optional
+        interval for how often to update the `stepsize`
+    disp : bool, optional
+        Set to True to print status messages
+    niter_success : integer, optional
+        Stop the run if the global minimum candidate remains the same for this
+        number of iterations.
+    rng : `numpy.random.Generator`, optional
+        Pseudorandom number generator state. When `rng` is None, a new
+        `numpy.random.Generator` is created using entropy from the
+        operating system. Types other than `numpy.random.Generator` are
+        passed to `numpy.random.default_rng` to instantiate a ``Generator``.
+
+        The random numbers generated only affect the default Metropolis
+        `accept_test` and the default `take_step`. If you supply your own
+        `take_step` and `accept_test`, and these functions use random
+        number generation, then those functions are responsible for the state
+        of their random number generator.
+    target_accept_rate : float, optional
+        The target acceptance rate that is used to adjust the `stepsize`.
+        If the current acceptance rate is greater than the target,
+        then the `stepsize` is increased. Otherwise, it is decreased.
+        Range is (0, 1). Default is 0.5.
+
+        .. versionadded:: 1.8.0
+
+    stepwise_factor : float, optional
+        The `stepsize` is multiplied or divided by this stepwise factor upon
+        each update. Range is (0, 1). Default is 0.9.
+
+        .. versionadded:: 1.8.0
+
+    Returns
+    -------
+    res : OptimizeResult
+        The optimization result represented as a `OptimizeResult` object.
+        Important attributes are: ``x`` the solution array, ``fun`` the value
+        of the function at the solution, and ``message`` which describes the
+        cause of the termination. The ``OptimizeResult`` object returned by the
+        selected minimizer at the lowest minimum is also contained within this
+        object and can be accessed through the ``lowest_optimization_result``
+        attribute. ``lowest_optimization_result`` will only be updated if a
+        local minimization was successful.          
+        See `OptimizeResult` for a description of other attributes.
+
+    See Also
+    --------
+    minimize :
+        The local minimization function called once for each basinhopping step.
+        `minimizer_kwargs` is passed to this routine.
+
+    Notes
+    -----
+    Basin-hopping is a stochastic algorithm which attempts to find the global
+    minimum of a smooth scalar function of one or more variables [1]_ [2]_ [3]_
+    [4]_. The algorithm in its current form was described by David Wales and
+    Jonathan Doye [2]_ http://www-wales.ch.cam.ac.uk/.
+
+    The algorithm is iterative with each cycle composed of the following
+    features
+
+    1) random perturbation of the coordinates
+
+    2) local minimization
+
+    3) accept or reject the new coordinates based on the minimized function
+       value
+
+    The acceptance test used here is the Metropolis criterion of standard Monte
+    Carlo algorithms, although there are many other possibilities [3]_.
+
+    This global minimization method has been shown to be extremely efficient
+    for a wide variety of problems in physics and chemistry. It is
+    particularly useful when the function has many minima separated by large
+    barriers. See the `Cambridge Cluster Database
+    <https://www-wales.ch.cam.ac.uk/CCD.html>`_ for databases of molecular
+    systems that have been optimized primarily using basin-hopping. This
+    database includes minimization problems exceeding 300 degrees of freedom.
+
+    See the free software program `GMIN <https://www-wales.ch.cam.ac.uk/GMIN>`_
+    for a Fortran implementation of basin-hopping. This implementation has many
+    variations of the procedure described above, including more
+    advanced step taking algorithms and alternate acceptance criterion.
+
+    For stochastic global optimization there is no way to determine if the true
+    global minimum has actually been found. Instead, as a consistency check,
+    the algorithm can be run from a number of different random starting points
+    to ensure the lowest minimum found in each example has converged to the
+    global minimum. For this reason, `basinhopping` will by default simply
+    run for the number of iterations `niter` and return the lowest minimum
+    found. It is left to the user to ensure that this is in fact the global
+    minimum.
+
+    Choosing `stepsize`:  This is a crucial parameter in `basinhopping` and
+    depends on the problem being solved. The step is chosen uniformly in the
+    region from x0-stepsize to x0+stepsize, in each dimension. Ideally, it
+    should be comparable to the typical separation (in argument values) between
+    local minima of the function being optimized. `basinhopping` will, by
+    default, adjust `stepsize` to find an optimal value, but this may take
+    many iterations. You will get quicker results if you set a sensible
+    initial value for ``stepsize``.
+
+    Choosing `T`: The parameter `T` is the "temperature" used in the
+    Metropolis criterion. Basinhopping steps are always accepted if
+    ``func(xnew) < func(xold)``. Otherwise, they are accepted with
+    probability::
+
+        exp( -(func(xnew) - func(xold)) / T )
+
+    So, for best results, `T` should to be comparable to the typical
+    difference (in function values) between local minima. (The height of
+    "walls" between local minima is irrelevant.)
+
+    If `T` is 0, the algorithm becomes Monotonic Basin-Hopping, in which all
+    steps that increase energy are rejected.
+
+    .. versionadded:: 0.12.0
+
+    References
+    ----------
+    .. [1] Wales, David J. 2003, Energy Landscapes, Cambridge University Press,
+        Cambridge, UK.
+    .. [2] Wales, D J, and Doye J P K, Global Optimization by Basin-Hopping and
+        the Lowest Energy Structures of Lennard-Jones Clusters Containing up to
+        110 Atoms.  Journal of Physical Chemistry A, 1997, 101, 5111.
+    .. [3] Li, Z. and Scheraga, H. A., Monte Carlo-minimization approach to the
+        multiple-minima problem in protein folding, Proc. Natl. Acad. Sci. USA,
+        1987, 84, 6611.
+    .. [4] Wales, D. J. and Scheraga, H. A., Global optimization of clusters,
+        crystals, and biomolecules, Science, 1999, 285, 1368.
+    .. [5] Olson, B., Hashmi, I., Molloy, K., and Shehu1, A., Basin Hopping as
+        a General and Versatile Optimization Framework for the Characterization
+        of Biological Macromolecules, Advances in Artificial Intelligence,
+        Volume 2012 (2012), Article ID 674832, :doi:`10.1155/2012/674832`
+
+    Examples
+    --------
+    The following example is a 1-D minimization problem, with many
+    local minima superimposed on a parabola.
+
+    >>> import numpy as np
+    >>> from scipy.optimize import basinhopping
+    >>> func = lambda x: np.cos(14.5 * x - 0.3) + (x + 0.2) * x
+    >>> x0 = [1.]
+
+    Basinhopping, internally, uses a local minimization algorithm. We will use
+    the parameter `minimizer_kwargs` to tell basinhopping which algorithm to
+    use and how to set up that minimizer. This parameter will be passed to
+    `scipy.optimize.minimize`.
+
+    >>> minimizer_kwargs = {"method": "BFGS"}
+    >>> ret = basinhopping(func, x0, minimizer_kwargs=minimizer_kwargs,
+    ...                    niter=200)
+    >>> # the global minimum is:
+    >>> ret.x, ret.fun
+    -0.1951, -1.0009
+
+    Next consider a 2-D minimization problem. Also, this time, we
+    will use gradient information to significantly speed up the search.
+
+    >>> def func2d(x):
+    ...     f = np.cos(14.5 * x[0] - 0.3) + (x[1] + 0.2) * x[1] + (x[0] +
+    ...                                                            0.2) * x[0]
+    ...     df = np.zeros(2)
+    ...     df[0] = -14.5 * np.sin(14.5 * x[0] - 0.3) + 2. * x[0] + 0.2
+    ...     df[1] = 2. * x[1] + 0.2
+    ...     return f, df
+
+    We'll also use a different local minimization algorithm. Also, we must tell
+    the minimizer that our function returns both energy and gradient (Jacobian).
+
+    >>> minimizer_kwargs = {"method":"L-BFGS-B", "jac":True}
+    >>> x0 = [1.0, 1.0]
+    >>> ret = basinhopping(func2d, x0, minimizer_kwargs=minimizer_kwargs,
+    ...                    niter=200)
+    >>> print("global minimum: x = [%.4f, %.4f], f(x) = %.4f" % (ret.x[0],
+    ...                                                           ret.x[1],
+    ...                                                           ret.fun))
+    global minimum: x = [-0.1951, -0.1000], f(x) = -1.0109
+
+    Here is an example using a custom step-taking routine. Imagine you want
+    the first coordinate to take larger steps than the rest of the coordinates.
+    This can be implemented like so:
+
+    >>> class MyTakeStep:
+    ...    def __init__(self, stepsize=0.5):
+    ...        self.stepsize = stepsize
+    ...        self.rng = np.random.default_rng()
+    ...    def __call__(self, x):
+    ...        s = self.stepsize
+    ...        x[0] += self.rng.uniform(-2.*s, 2.*s)
+    ...        x[1:] += self.rng.uniform(-s, s, x[1:].shape)
+    ...        return x
+
+    Since ``MyTakeStep.stepsize`` exists basinhopping will adjust the magnitude
+    of `stepsize` to optimize the search. We'll use the same 2-D function as
+    before
+
+    >>> mytakestep = MyTakeStep()
+    >>> ret = basinhopping(func2d, x0, minimizer_kwargs=minimizer_kwargs,
+    ...                    niter=200, take_step=mytakestep)
+    >>> print("global minimum: x = [%.4f, %.4f], f(x) = %.4f" % (ret.x[0],
+    ...                                                           ret.x[1],
+    ...                                                           ret.fun))
+    global minimum: x = [-0.1951, -0.1000], f(x) = -1.0109
+
+    Now, let's do an example using a custom callback function which prints the
+    value of every minimum found
+
+    >>> def print_fun(x, f, accepted):
+    ...         print("at minimum %.4f accepted %d" % (f, int(accepted)))
+
+    We'll run it for only 10 basinhopping steps this time.
+
+    >>> rng = np.random.default_rng()
+    >>> ret = basinhopping(func2d, x0, minimizer_kwargs=minimizer_kwargs,
+    ...                    niter=10, callback=print_fun, rng=rng)
+    at minimum 0.4159 accepted 1
+    at minimum -0.4317 accepted 1
+    at minimum -1.0109 accepted 1
+    at minimum -0.9073 accepted 1
+    at minimum -0.4317 accepted 0
+    at minimum -0.1021 accepted 1
+    at minimum -0.7425 accepted 1
+    at minimum -0.9073 accepted 1
+    at minimum -0.4317 accepted 0
+    at minimum -0.7425 accepted 1
+    at minimum -0.9073 accepted 1
+
+    The minimum at -1.0109 is actually the global minimum, found already on the
+    8th iteration.
+
+    """ # numpy/numpydoc#87  # noqa: E501
+    if target_accept_rate <= 0. or target_accept_rate >= 1.:
+        raise ValueError('target_accept_rate has to be in range (0, 1)')
+    if stepwise_factor <= 0. or stepwise_factor >= 1.:
+        raise ValueError('stepwise_factor has to be in range (0, 1)')
+
+    x0 = np.array(x0)
+
+    # set up the np.random generator
+    rng = check_random_state(rng)
+
+    # set up minimizer
+    if minimizer_kwargs is None:
+        minimizer_kwargs = dict()
+    wrapped_minimizer = MinimizerWrapper(scipy.optimize.minimize, func,
+                                         **minimizer_kwargs)
+
+    # set up step-taking algorithm
+    if take_step is not None:
+        if not callable(take_step):
+            raise TypeError("take_step must be callable")
+        # if take_step.stepsize exists then use AdaptiveStepsize to control
+        # take_step.stepsize
+        if hasattr(take_step, "stepsize"):
+            take_step_wrapped = AdaptiveStepsize(
+                take_step, interval=interval,
+                accept_rate=target_accept_rate,
+                factor=stepwise_factor,
+                verbose=disp)
+        else:
+            take_step_wrapped = take_step
+    else:
+        # use default
+        displace = RandomDisplacement(stepsize=stepsize, rng=rng)
+        take_step_wrapped = AdaptiveStepsize(displace, interval=interval,
+                                             accept_rate=target_accept_rate,
+                                             factor=stepwise_factor,
+                                             verbose=disp)
+
+    # set up accept tests
+    accept_tests = []
+    if accept_test is not None:
+        if not callable(accept_test):
+            raise TypeError("accept_test must be callable")
+        accept_tests = [accept_test]
+
+    # use default
+    metropolis = Metropolis(T, rng=rng)
+    accept_tests.append(metropolis)
+
+    if niter_success is None:
+        niter_success = niter + 2
+
+    bh = BasinHoppingRunner(x0, wrapped_minimizer, take_step_wrapped,
+                            accept_tests, disp=disp)
+
+    # The wrapped minimizer is called once during construction of
+    # BasinHoppingRunner, so run the callback
+    if callable(callback):
+        callback(bh.storage.minres.x, bh.storage.minres.fun, True)
+
+    # start main iteration loop
+    count, i = 0, 0
+    message = ["requested number of basinhopping iterations completed"
+               " successfully"]
+    for i in range(niter):
+        new_global_min = bh.one_cycle()
+
+        if callable(callback):
+            # should we pass a copy of x?
+            val = callback(bh.xtrial, bh.energy_trial, bh.accept)
+            if val is not None:
+                if val:
+                    message = ["callback function requested stop early by"
+                               "returning True"]
+                    break
+
+        count += 1
+        if new_global_min:
+            count = 0
+        elif count > niter_success:
+            message = ["success condition satisfied"]
+            break
+
+    # prepare return object
+    res = bh.res
+    res.lowest_optimization_result = bh.storage.get_lowest()
+    res.x = np.copy(res.lowest_optimization_result.x)
+    res.fun = res.lowest_optimization_result.fun
+    res.message = message
+    res.nit = i + 1
+    res.success = res.lowest_optimization_result.success
+    return res

venv/lib/python3.13/site-packages/scipy/optimize/_bracket.py

@@ -0,0 +1,706 @@
+import numpy as np
+import scipy._lib._elementwise_iterative_method as eim
+from scipy._lib._util import _RichResult
+from scipy._lib._array_api import array_namespace, xp_ravel, xp_promote
+
+_ELIMITS = -1  # used in _bracket_root
+_ESTOPONESIDE = 2  # used in _bracket_root
+
+def _bracket_root_iv(func, xl0, xr0, xmin, xmax, factor, args, maxiter):
+
+    if not callable(func):
+        raise ValueError('`func` must be callable.')
+
+    if not np.iterable(args):
+        args = (args,)
+
+    xp = array_namespace(xl0, xr0, xmin, xmax, factor, *args)
+
+    # If xr0 is not supplied, fill with a dummy value for the sake of
+    # broadcasting. We need to wait until xmax has been validated to
+    # compute the default value.
+    xr0_not_supplied = False
+    if xr0 is None:
+        xr0 = xp.nan
+        xr0_not_supplied = True
+
+    xmin = -xp.inf if xmin is None else xmin
+    xmax = xp.inf if xmax is None else xmax
+    factor = 2. if factor is None else factor
+    xl0, xr0, xmin, xmax, factor = xp_promote(
+        xl0, xr0, xmin, xmax, factor, broadcast=True, force_floating=True, xp=xp)
+
+    if not xp.isdtype(xl0.dtype, ('integral', 'real floating')):
+        raise ValueError('`xl0` must be numeric and real.')
+
+    if (not xp.isdtype(xr0.dtype, "numeric")
+        or xp.isdtype(xr0.dtype, "complex floating")):
+        raise ValueError('`xr0` must be numeric and real.')
+
+    if (not xp.isdtype(xmin.dtype, "numeric")
+        or xp.isdtype(xmin.dtype, "complex floating")):
+        raise ValueError('`xmin` must be numeric and real.')
+
+    if (not xp.isdtype(xmax.dtype, "numeric")
+        or xp.isdtype(xmax.dtype, "complex floating")):
+        raise ValueError('`xmax` must be numeric and real.')
+
+    if (not xp.isdtype(factor.dtype, "numeric")
+        or xp.isdtype(factor.dtype, "complex floating")):
+        raise ValueError('`factor` must be numeric and real.')
+    if not xp.all(factor > 1):
+        raise ValueError('All elements of `factor` must be greater than 1.')
+
+    # Calculate the default value of xr0 if a value has not been supplied.
+    # Be careful to ensure xr0 is not larger than xmax.
+    if xr0_not_supplied:
+        xr0 = xl0 + xp.minimum((xmax - xl0)/ 8, 1.0)
+        xr0 = xp.astype(xr0, xl0.dtype, copy=False)
+
+    maxiter = xp.asarray(maxiter)
+    message = '`maxiter` must be a non-negative integer.'
+    if (not xp.isdtype(maxiter.dtype, "numeric") or maxiter.shape != tuple()
+            or xp.isdtype(maxiter.dtype, "complex floating")):
+        raise ValueError(message)
+    maxiter_int = int(maxiter[()])
+    if not maxiter == maxiter_int or maxiter < 0:
+        raise ValueError(message)
+
+    return func, xl0, xr0, xmin, xmax, factor, args, maxiter, xp
+
+
+def _bracket_root(func, xl0, xr0=None, *, xmin=None, xmax=None, factor=None,
+                  args=(), maxiter=1000):
+    """Bracket the root of a monotonic scalar function of one variable
+
+    This function works elementwise when `xl0`, `xr0`, `xmin`, `xmax`, `factor`, and
+    the elements of `args` are broadcastable arrays.
+
+    Parameters
+    ----------
+    func : callable
+        The function for which the root is to be bracketed.
+        The signature must be::
+
+            func(x: ndarray, *args) -> ndarray
+
+        where each element of ``x`` is a finite real and ``args`` is a tuple,
+        which may contain an arbitrary number of arrays that are broadcastable
+        with `x`. ``func`` must be an elementwise function: each element
+        ``func(x)[i]`` must equal ``func(x[i])`` for all indices ``i``.
+    xl0, xr0: float array_like
+        Starting guess of bracket, which need not contain a root. If `xr0` is
+        not provided, ``xr0 = xl0 + 1``. Must be broadcastable with one another.
+    xmin, xmax : float array_like, optional
+        Minimum and maximum allowable endpoints of the bracket, inclusive. Must
+        be broadcastable with `xl0` and `xr0`.
+    factor : float array_like, default: 2
+        The factor used to grow the bracket. See notes for details.
+    args : tuple, optional
+        Additional positional arguments to be passed to `func`.  Must be arrays
+        broadcastable with `xl0`, `xr0`, `xmin`, and `xmax`. If the callable to be
+        bracketed requires arguments that are not broadcastable with these
+        arrays, wrap that callable with `func` such that `func` accepts
+        only `x` and broadcastable arrays.
+    maxiter : int, optional
+        The maximum number of iterations of the algorithm to perform.
+
+    Returns
+    -------
+    res : _RichResult
+        An instance of `scipy._lib._util._RichResult` with the following
+        attributes. The descriptions are written as though the values will be
+        scalars; however, if `func` returns an array, the outputs will be
+        arrays of the same shape.
+
+        xl, xr : float
+            The lower and upper ends of the bracket, if the algorithm
+            terminated successfully.
+        fl, fr : float
+            The function value at the lower and upper ends of the bracket.
+        nfev : int
+            The number of function evaluations required to find the bracket.
+            This is distinct from the number of times `func` is *called*
+            because the function may evaluated at multiple points in a single
+            call.
+        nit : int
+            The number of iterations of the algorithm that were performed.
+        status : int
+            An integer representing the exit status of the algorithm.
+
+            - ``0`` : The algorithm produced a valid bracket.
+            - ``-1`` : The bracket expanded to the allowable limits without finding a bracket.
+            - ``-2`` : The maximum number of iterations was reached.
+            - ``-3`` : A non-finite value was encountered.
+            - ``-4`` : Iteration was terminated by `callback`.
+            - ``-5``: The initial bracket does not satisfy `xmin <= xl0 < xr0 < xmax`.
+            - ``1`` : The algorithm is proceeding normally (in `callback` only).
+            - ``2`` : A bracket was found in the opposite search direction (in `callback` only).
+
+        success : bool
+            ``True`` when the algorithm terminated successfully (status ``0``).
+
+    Notes
+    -----
+    This function generalizes an algorithm found in pieces throughout
+    `scipy.stats`. The strategy is to iteratively grow the bracket ``(l, r)``
+     until ``func(l) < 0 < func(r)``. The bracket grows to the left as follows.
+
+    - If `xmin` is not provided, the distance between `xl0` and `l` is iteratively
+      increased by `factor`.
+    - If `xmin` is provided, the distance between `xmin` and `l` is iteratively
+      decreased by `factor`. Note that this also *increases* the bracket size.
+
+    Growth of the bracket to the right is analogous.
+
+    Growth of the bracket in one direction stops when the endpoint is no longer
+    finite, the function value at the endpoint is no longer finite, or the
+    endpoint reaches its limiting value (`xmin` or `xmax`). Iteration terminates
+    when the bracket stops growing in both directions, the bracket surrounds
+    the root, or a root is found (accidentally).
+
+    If two brackets are found - that is, a bracket is found on both sides in
+    the same iteration, the smaller of the two is returned.
+    If roots of the function are found, both `l` and `r` are set to the
+    leftmost root.
+
+    """  # noqa: E501
+    # Todo:
+    # - find bracket with sign change in specified direction
+    # - Add tolerance
+    # - allow factor < 1?
+
+    callback = None  # works; I just don't want to test it
+    temp = _bracket_root_iv(func, xl0, xr0, xmin, xmax, factor, args, maxiter)
+    func, xl0, xr0, xmin, xmax, factor, args, maxiter, xp = temp
+
+    xs = (xl0, xr0)
+    temp = eim._initialize(func, xs, args)
+    func, xs, fs, args, shape, dtype, xp = temp  # line split for PEP8
+    xl0, xr0 = xs
+    xmin = xp_ravel(xp.astype(xp.broadcast_to(xmin, shape), dtype, copy=False), xp=xp)
+    xmax = xp_ravel(xp.astype(xp.broadcast_to(xmax, shape), dtype, copy=False), xp=xp)
+    invalid_bracket = ~((xmin <= xl0) & (xl0 < xr0) & (xr0 <= xmax))
+
+    # The approach is to treat the left and right searches as though they were
+    # (almost) totally independent one-sided bracket searches. (The interaction
+    # is considered when checking for termination and preparing the result
+    # object.)
+    # `x` is the "moving" end of the bracket
+    x = xp.concat(xs)
+    f = xp.concat(fs)
+    invalid_bracket = xp.concat((invalid_bracket, invalid_bracket))
+    n = x.shape[0] // 2
+
+    # `x_last` is the previous location of the moving end of the bracket. If
+    # the signs of `f` and `f_last` are different, `x` and `x_last` form a
+    # bracket.
+    x_last = xp.concat((x[n:], x[:n]))
+    f_last = xp.concat((f[n:], f[:n]))
+    # `x0` is the "fixed" end of the bracket.
+    x0 = x_last
+    # We don't need to retain the corresponding function value, since the
+    # fixed end of the bracket is only needed to compute the new value of the
+    # moving end; it is never returned.
+    limit = xp.concat((xmin, xmax))
+
+    factor = xp_ravel(xp.broadcast_to(factor, shape), xp=xp)
+    factor = xp.astype(factor, dtype, copy=False)
+    factor = xp.concat((factor, factor))
+
+    active = xp.arange(2*n)
+    args = [xp.concat((arg, arg)) for arg in args]
+
+    # This is needed due to inner workings of `eim._loop`.
+    # We're abusing it a tiny bit.
+    shape = shape + (2,)
+
+    # `d` is for "distance".
+    # For searches without a limit, the distance between the fixed end of the
+    # bracket `x0` and the moving end `x` will grow by `factor` each iteration.
+    # For searches with a limit, the distance between the `limit` and moving
+    # end of the bracket `x` will shrink by `factor` each iteration.
+    i = xp.isinf(limit)
+    ni = ~i
+    d = xp.zeros_like(x)
+    d[i] = x[i] - x0[i]
+    d[ni] = limit[ni] - x[ni]
+
+    status = xp.full_like(x, eim._EINPROGRESS, dtype=xp.int32)  # in progress
+    status[invalid_bracket] = eim._EINPUTERR
+    nit, nfev = 0, 1  # one function evaluation per side performed above
+
+    work = _RichResult(x=x, x0=x0, f=f, limit=limit, factor=factor,
+                       active=active, d=d, x_last=x_last, f_last=f_last,
+                       nit=nit, nfev=nfev, status=status, args=args,
+                       xl=xp.nan, xr=xp.nan, fl=xp.nan, fr=xp.nan, n=n)
+    res_work_pairs = [('status', 'status'), ('xl', 'xl'), ('xr', 'xr'),
+                      ('nit', 'nit'), ('nfev', 'nfev'), ('fl', 'fl'),
+                      ('fr', 'fr'), ('x', 'x'), ('f', 'f'),
+                      ('x_last', 'x_last'), ('f_last', 'f_last')]
+
+    def pre_func_eval(work):
+        # Initialize moving end of bracket
+        x = xp.zeros_like(work.x)
+
+        # Unlimited brackets grow by `factor` by increasing distance from fixed
+        # end to moving end.
+        i = xp.isinf(work.limit)  # indices of unlimited brackets
+        work.d[i] *= work.factor[i]
+        x[i] = work.x0[i] + work.d[i]
+
+        # Limited brackets grow by decreasing the distance from the limit to
+        # the moving end.
+        ni = ~i  # indices of limited brackets
+        work.d[ni] /= work.factor[ni]
+        x[ni] = work.limit[ni] - work.d[ni]
+
+        return x
+
+    def post_func_eval(x, f, work):
+        # Keep track of the previous location of the moving end so that we can
+        # return a narrower bracket. (The alternative is to remember the
+        # original fixed end, but then the bracket would be wider than needed.)
+        work.x_last = work.x
+        work.f_last = work.f
+        work.x = x
+        work.f = f
+
+    def check_termination(work):
+        # Condition 0: initial bracket is invalid
+        stop = (work.status == eim._EINPUTERR)
+
+        # Condition 1: a valid bracket (or the root itself) has been found
+        sf = xp.sign(work.f)
+        sf_last = xp.sign(work.f_last)
+        i = ((sf_last == -sf) | (sf_last == 0) | (sf == 0)) & ~stop
+        work.status[i] = eim._ECONVERGED
+        stop[i] = True
+
+        # Condition 2: the other side's search found a valid bracket.
+        # (If we just found a bracket with the rightward search, we can stop
+        #  the leftward search, and vice-versa.)
+        # To do this, we need to set the status of the other side's search;
+        # this is tricky because `work.status` contains only the *active*
+        # elements, so we don't immediately know the index of the element we
+        # need to set - or even if it's still there. (That search may have
+        # terminated already, e.g. by reaching its `limit`.)
+        # To facilitate this, `work.active` contains a unit integer index of
+        # each search. Index `k` (`k < n)` and `k + n` correspond with a
+        # leftward and rightward search, respectively. Elements are removed
+        # from `work.active` just as they are removed from `work.status`, so
+        # we use `work.active` to help find the right location in
+        # `work.status`.
+        # Get the integer indices of the elements that can also stop
+        also_stop = (work.active[i] + work.n) % (2*work.n)
+        # Check whether they are still active. We want to find the indices
+        # in work.active where the associated values in work.active are
+        # contained in also_stop. xp.searchsorted let's us take advantage
+        # of work.active being sorted, but requires some hackery because
+        # searchsorted solves the separate but related problem of finding
+        # the indices where the values in also_stop should be added to
+        # maintain sorted order.
+        j = xp.searchsorted(work.active, also_stop)
+        # If the location exceeds the length of the `work.active`, they are
+        # not there. This happens when a value in also_stop is larger than
+        # the greatest value in work.active. This case needs special handling
+        # because we cannot simply check that also_stop == work.active[j].
+        mask = j < work.active.shape[0]
+        # Note that we also have to use the mask to filter also_stop to ensure
+        # that also_stop and j will still have the same shape.
+        j, also_stop = j[mask], also_stop[mask]
+        j = j[also_stop == work.active[j]]
+        # Now convert these to boolean indices to use with `work.status`.
+        i = xp.zeros_like(stop)
+        i[j] = True  # boolean indices of elements that can also stop
+        i = i & ~stop
+        work.status[i] = _ESTOPONESIDE
+        stop[i] = True
+
+        # Condition 3: moving end of bracket reaches limit
+        i = (work.x == work.limit) & ~stop
+        work.status[i] = _ELIMITS
+        stop[i] = True
+
+        # Condition 4: non-finite value encountered
+        i = ~(xp.isfinite(work.x) & xp.isfinite(work.f)) & ~stop
+        work.status[i] = eim._EVALUEERR
+        stop[i] = True
+
+        return stop
+
+    def post_termination_check(work):
+        pass
+
+    def customize_result(res, shape):
+        n = res['x'].shape[0] // 2
+
+        # To avoid ambiguity, below we refer to `xl0`, the initial left endpoint
+        # as `a` and `xr0`, the initial right endpoint, as `b`.
+        # Because we treat the two one-sided searches as though they were
+        # independent, what we keep track of in `work` and what we want to
+        # return in `res` look quite different. Combine the results from the
+        # two one-sided searches before reporting the results to the user.
+        # - "a" refers to the leftward search (the moving end started at `a`)
+        # - "b" refers to the rightward search (the moving end started at `b`)
+        # - "l" refers to the left end of the bracket (closer to -oo)
+        # - "r" refers to the right end of the bracket (closer to +oo)
+        xal = res['x'][:n]
+        xar = res['x_last'][:n]
+        xbl = res['x_last'][n:]
+        xbr = res['x'][n:]
+
+        fal = res['f'][:n]
+        far = res['f_last'][:n]
+        fbl = res['f_last'][n:]
+        fbr = res['f'][n:]
+
+        # Initialize the brackets and corresponding function values to return
+        # to the user. Brackets may not be valid (e.g. there is no root,
+        # there weren't enough iterations, NaN encountered), but we still need
+        # to return something. One option would be all NaNs, but what I've
+        # chosen here is the left- and right-most points at which the function
+        # has been evaluated. This gives the user some information about what
+        # interval of the real line has been searched and shows that there is
+        # no sign change between the two ends.
+        xl = xp.asarray(xal, copy=True)
+        fl = xp.asarray(fal, copy=True)
+        xr = xp.asarray(xbr, copy=True)
+        fr = xp.asarray(fbr, copy=True)
+
+        # `status` indicates whether the bracket is valid or not. If so,
+        # we want to adjust the bracket we return to be the narrowest possible
+        # given the points at which we evaluated the function.
+        # For example if bracket "a" is valid and smaller than bracket "b" OR
+        # if bracket "a" is valid and bracket "b" is not valid, we want to
+        # return bracket "a" (and vice versa).
+        sa = res['status'][:n]
+        sb = res['status'][n:]
+
+        da = xar - xal
+        db = xbr - xbl
+
+        i1 = ((da <= db) & (sa == 0)) | ((sa == 0) & (sb != 0))
+        i2 = ((db <= da) & (sb == 0)) | ((sb == 0) & (sa != 0))
+
+        xr[i1] = xar[i1]
+        fr[i1] = far[i1]
+        xl[i2] = xbl[i2]
+        fl[i2] = fbl[i2]
+
+        # Finish assembling the result object
+        res['xl'] = xl
+        res['xr'] = xr
+        res['fl'] = fl
+        res['fr'] = fr
+
+        res['nit'] = xp.maximum(res['nit'][:n], res['nit'][n:])
+        res['nfev'] = res['nfev'][:n] + res['nfev'][n:]
+        # If the status on one side is zero, the status is zero. In any case,
+        # report the status from one side only.
+        res['status'] = xp.where(sa == 0, sa, sb)
+        res['success'] = (res['status'] == 0)
+
+        del res['x']
+        del res['f']
+        del res['x_last']
+        del res['f_last']
+
+        return shape[:-1]
+
+    return eim._loop(work, callback, shape, maxiter, func, args, dtype,
+                     pre_func_eval, post_func_eval, check_termination,
+                     post_termination_check, customize_result, res_work_pairs,
+                     xp)
+
+
+def _bracket_minimum_iv(func, xm0, xl0, xr0, xmin, xmax, factor, args, maxiter):
+
+    if not callable(func):
+        raise ValueError('`func` must be callable.')
+
+    if not np.iterable(args):
+        args = (args,)
+
+    xp = array_namespace(xm0, xl0, xr0, xmin, xmax, factor, *args)
+
+    xmin = -xp.inf if xmin is None else xmin
+    xmax = xp.inf if xmax is None else xmax
+
+    # If xl0 (xr0) is not supplied, fill with a dummy value for the sake
+    # of broadcasting. We need to wait until xmin (xmax) has been validated
+    # to compute the default values.
+    xl0_not_supplied = False
+    if xl0 is None:
+        xl0 = xp.nan
+        xl0_not_supplied = True
+
+    xr0_not_supplied = False
+    if xr0 is None:
+        xr0 = xp.nan
+        xr0_not_supplied = True
+
+    factor = 2.0 if factor is None else factor
+
+    xm0, xl0, xr0, xmin, xmax, factor = xp_promote(
+        xm0, xl0, xr0, xmin, xmax, factor, broadcast=True, force_floating=True, xp=xp)
+
+    if not xp.isdtype(xm0.dtype, ('integral', 'real floating')):
+        raise ValueError('`xm0` must be numeric and real.')
+
+    if (not xp.isdtype(xl0.dtype, "numeric")
+        or xp.isdtype(xl0.dtype, "complex floating")):
+        raise ValueError('`xl0` must be numeric and real.')
+
+    if (not xp.isdtype(xr0.dtype, "numeric")
+        or xp.isdtype(xr0.dtype, "complex floating")):
+        raise ValueError('`xr0` must be numeric and real.')
+
+    if (not xp.isdtype(xmin.dtype, "numeric")
+        or xp.isdtype(xmin.dtype, "complex floating")):
+        raise ValueError('`xmin` must be numeric and real.')
+
+    if (not xp.isdtype(xmax.dtype, "numeric")
+        or xp.isdtype(xmax.dtype, "complex floating")):
+        raise ValueError('`xmax` must be numeric and real.')
+
+    if (not xp.isdtype(factor.dtype, "numeric")
+        or xp.isdtype(factor.dtype, "complex floating")):
+        raise ValueError('`factor` must be numeric and real.')
+    if not xp.all(factor > 1):
+        raise ValueError('All elements of `factor` must be greater than 1.')
+
+    # Calculate default values of xl0 and/or xr0 if they have not been supplied
+    # by the user. We need to be careful to ensure xl0 and xr0 are not outside
+    # of (xmin, xmax).
+    if xl0_not_supplied:
+        xl0 = xm0 - xp.minimum((xm0 - xmin)/16, 0.5)
+        xl0 = xp.astype(xl0, xm0.dtype, copy=False)
+    if xr0_not_supplied:
+        xr0 = xm0 + xp.minimum((xmax - xm0)/16, 0.5)
+        xr0 = xp.astype(xr0, xm0.dtype, copy=False)
+
+    maxiter = xp.asarray(maxiter)
+    message = '`maxiter` must be a non-negative integer.'
+    if (not xp.isdtype(maxiter.dtype, "numeric") or maxiter.shape != tuple()
+            or xp.isdtype(maxiter.dtype, "complex floating")):
+        raise ValueError(message)
+    maxiter_int = int(maxiter[()])
+    if not maxiter == maxiter_int or maxiter < 0:
+        raise ValueError(message)
+
+    return func, xm0, xl0, xr0, xmin, xmax, factor, args, maxiter, xp
+
+
+def _bracket_minimum(func, xm0, *, xl0=None, xr0=None, xmin=None, xmax=None,
+                     factor=None, args=(), maxiter=1000):
+    """Bracket the minimum of a unimodal scalar function of one variable
+
+    This function works elementwise when `xm0`, `xl0`, `xr0`, `xmin`, `xmax`,
+    and the elements of `args` are broadcastable arrays.
+
+    Parameters
+    ----------
+    func : callable
+        The function for which the minimum is to be bracketed.
+        The signature must be::
+
+            func(x: ndarray, *args) -> ndarray
+
+        where each element of ``x`` is a finite real and ``args`` is a tuple,
+        which may contain an arbitrary number of arrays that are broadcastable
+        with ``x``. `func` must be an elementwise function: each element
+        ``func(x)[i]`` must equal ``func(x[i])`` for all indices `i`.
+    xm0: float array_like
+        Starting guess for middle point of bracket.
+    xl0, xr0: float array_like, optional
+        Starting guesses for left and right endpoints of the bracket. Must be
+        broadcastable with one another and with `xm0`.
+    xmin, xmax : float array_like, optional
+        Minimum and maximum allowable endpoints of the bracket, inclusive. Must
+        be broadcastable with `xl0`, `xm0`, and `xr0`.
+    factor : float array_like, optional
+        Controls expansion of bracket endpoint in downhill direction. Works
+        differently in the cases where a limit is set in the downhill direction
+        with `xmax` or `xmin`. See Notes.
+    args : tuple, optional
+        Additional positional arguments to be passed to `func`.  Must be arrays
+        broadcastable with `xl0`, `xm0`, `xr0`, `xmin`, and `xmax`. If the
+        callable to be bracketed requires arguments that are not broadcastable
+        with these arrays, wrap that callable with `func` such that `func`
+        accepts only ``x`` and broadcastable arrays.
+    maxiter : int, optional
+        The maximum number of iterations of the algorithm to perform. The number
+        of function evaluations is three greater than the number of iterations.
+
+    Returns
+    -------
+    res : _RichResult
+        An instance of `scipy._lib._util._RichResult` with the following
+        attributes. The descriptions are written as though the values will be
+        scalars; however, if `func` returns an array, the outputs will be
+        arrays of the same shape.
+
+        xl, xm, xr : float
+            The left, middle, and right points of the bracket, if the algorithm
+            terminated successfully.
+        fl, fm, fr : float
+            The function value at the left, middle, and right points of the bracket.
+        nfev : int
+            The number of function evaluations required to find the bracket.
+        nit : int
+            The number of iterations of the algorithm that were performed.
+        status : int
+            An integer representing the exit status of the algorithm.
+
+            - ``0`` : The algorithm produced a valid bracket.
+            - ``-1`` : The bracket expanded to the allowable limits. Assuming
+                       unimodality, this implies the endpoint at the limit is a
+                       minimizer.
+            - ``-2`` : The maximum number of iterations was reached.
+            - ``-3`` : A non-finite value was encountered.
+            - ``-4`` : ``None`` shall pass.
+            - ``-5`` : The initial bracket does not satisfy
+                       `xmin <= xl0 < xm0 < xr0 <= xmax`.
+
+        success : bool
+            ``True`` when the algorithm terminated successfully (status ``0``).
+
+    Notes
+    -----
+    Similar to `scipy.optimize.bracket`, this function seeks to find real
+    points ``xl < xm < xr`` such that ``f(xl) >= f(xm)`` and ``f(xr) >= f(xm)``,
+    where at least one of the inequalities is strict. Unlike `scipy.optimize.bracket`,
+    this function can operate in a vectorized manner on array input, so long as
+    the input arrays are broadcastable with each other. Also unlike
+    `scipy.optimize.bracket`, users may specify minimum and maximum endpoints
+    for the desired bracket.
+
+    Given an initial trio of points ``xl = xl0``, ``xm = xm0``, ``xr = xr0``,
+    the algorithm checks if these points already give a valid bracket. If not,
+    a new endpoint, ``w`` is chosen in the "downhill" direction, ``xm`` becomes the new
+    opposite endpoint, and either `xl` or `xr` becomes the new middle point,
+    depending on which direction is downhill. The algorithm repeats from here.
+
+    The new endpoint `w` is chosen differently depending on whether or not a
+    boundary `xmin` or `xmax` has been set in the downhill direction. Without
+    loss of generality, suppose the downhill direction is to the right, so that
+    ``f(xl) > f(xm) > f(xr)``. If there is no boundary to the right, then `w`
+    is chosen to be ``xr + factor * (xr - xm)`` where `factor` is controlled by
+    the user (defaults to 2.0) so that step sizes increase in geometric proportion.
+    If there is a boundary, `xmax` in this case, then `w` is chosen to be
+    ``xmax - (xmax - xr)/factor``, with steps slowing to a stop at
+    `xmax`. This cautious approach ensures that a minimum near but distinct from
+    the boundary isn't missed while also detecting whether or not the `xmax` is
+    a minimizer when `xmax` is reached after a finite number of steps.
+    """  # noqa: E501
+    callback = None  # works; I just don't want to test it
+
+    temp = _bracket_minimum_iv(func, xm0, xl0, xr0, xmin, xmax, factor, args, maxiter)
+    func, xm0, xl0, xr0, xmin, xmax, factor, args, maxiter, xp = temp
+
+    xs = (xl0, xm0, xr0)
+    temp = eim._initialize(func, xs, args)
+    func, xs, fs, args, shape, dtype, xp = temp
+
+    xl0, xm0, xr0 = xs
+    fl0, fm0, fr0 = fs
+    xmin = xp.astype(xp.broadcast_to(xmin, shape), dtype, copy=False)
+    xmin = xp_ravel(xmin, xp=xp)
+    xmax = xp.astype(xp.broadcast_to(xmax, shape), dtype, copy=False)
+    xmax = xp_ravel(xmax, xp=xp)
+    invalid_bracket = ~((xmin <= xl0) & (xl0 < xm0) & (xm0 < xr0) & (xr0 <= xmax))
+    # We will modify factor later on so make a copy. np.broadcast_to returns
+    # a read-only view.
+    factor = xp.astype(xp.broadcast_to(factor, shape), dtype, copy=True)
+    factor = xp_ravel(factor)
+
+    # To simplify the logic, swap xl and xr if f(xl) < f(xr). We should always be
+    # marching downhill in the direction from xl to xr.
+    comp = fl0 < fr0
+    xl0[comp], xr0[comp] = xr0[comp], xl0[comp]
+    fl0[comp], fr0[comp] = fr0[comp], fl0[comp]
+    # We only need the boundary in the direction we're traveling.
+    limit = xp.where(comp, xmin, xmax)
+
+    unlimited = xp.isinf(limit)
+    limited = ~unlimited
+    step = xp.empty_like(xl0)
+
+    step[unlimited] = (xr0[unlimited] - xm0[unlimited])
+    step[limited] = (limit[limited] - xr0[limited])
+
+    # Step size is divided by factor for case where there is a limit.
+    factor[limited] = 1 / factor[limited]
+
+    status = xp.full_like(xl0, eim._EINPROGRESS, dtype=xp.int32)
+    status[invalid_bracket] = eim._EINPUTERR
+    nit, nfev = 0, 3
+
+    work = _RichResult(xl=xl0, xm=xm0, xr=xr0, xr0=xr0, fl=fl0, fm=fm0, fr=fr0,
+                       step=step, limit=limit, limited=limited, factor=factor, nit=nit,
+                       nfev=nfev, status=status, args=args)
+
+    res_work_pairs = [('status', 'status'), ('xl', 'xl'), ('xm', 'xm'), ('xr', 'xr'),
+                      ('nit', 'nit'), ('nfev', 'nfev'), ('fl', 'fl'), ('fm', 'fm'),
+                      ('fr', 'fr')]
+
+    def pre_func_eval(work):
+        work.step *= work.factor
+        x = xp.empty_like(work.xr)
+        x[~work.limited] = work.xr0[~work.limited] + work.step[~work.limited]
+        x[work.limited] = work.limit[work.limited] - work.step[work.limited]
+        # Since the new bracket endpoint is calculated from an offset with the
+        # limit, it may be the case that the new endpoint equals the old endpoint,
+        # when the old endpoint is sufficiently close to the limit. We use the
+        # limit itself as the new endpoint in these cases.
+        x[work.limited] = xp.where(
+            x[work.limited] == work.xr[work.limited],
+            work.limit[work.limited],
+            x[work.limited],
+        )
+        return x
+
+    def post_func_eval(x, f, work):
+        work.xl, work.xm, work.xr = work.xm, work.xr, x
+        work.fl, work.fm, work.fr = work.fm, work.fr, f
+
+    def check_termination(work):
+        # Condition 0: Initial bracket is invalid.
+        stop = (work.status == eim._EINPUTERR)
+
+        # Condition 1: A valid bracket has been found.
+        i = (
+            (work.fl >= work.fm) & (work.fr > work.fm)
+            | (work.fl > work.fm) & (work.fr >= work.fm)
+        ) & ~stop
+        work.status[i] = eim._ECONVERGED
+        stop[i] = True
+
+        # Condition 2: Moving end of bracket reaches limit.
+        i = (work.xr == work.limit) & ~stop
+        work.status[i] = _ELIMITS
+        stop[i] = True
+
+        # Condition 3: non-finite value encountered
+        i = ~(xp.isfinite(work.xr) & xp.isfinite(work.fr)) & ~stop
+        work.status[i] = eim._EVALUEERR
+        stop[i] = True
+
+        return stop
+
+    def post_termination_check(work):
+        pass
+
+    def customize_result(res, shape):
+        # Reorder entries of xl and xr if they were swapped due to f(xl0) < f(xr0).
+        comp = res['xl'] > res['xr']
+        res['xl'][comp], res['xr'][comp] = res['xr'][comp], res['xl'][comp]
+        res['fl'][comp], res['fr'][comp] = res['fr'][comp], res['fl'][comp]
+        return shape
+
+    return eim._loop(work, callback, shape,
+                     maxiter, func, args, dtype,
+                     pre_func_eval, post_func_eval,
+                     check_termination, post_termination_check,
+                     customize_result, res_work_pairs, xp)

venv/lib/python3.13/site-packages/scipy/optimize/_chandrupatla.py

@@ -0,0 +1,551 @@
+import math
+import numpy as np
+import scipy._lib._elementwise_iterative_method as eim
+from scipy._lib._util import _RichResult
+from scipy._lib._array_api import xp_copy
+
+# TODO:
+# - (maybe?) don't use fancy indexing assignment
+# - figure out how to replace the new `try`/`except`s
+
+
+def _chandrupatla(func, a, b, *, args=(), xatol=None, xrtol=None,
+                  fatol=None, frtol=0, maxiter=None, callback=None):
+    """Find the root of an elementwise function using Chandrupatla's algorithm.
+
+    For each element of the output of `func`, `chandrupatla` seeks the scalar
+    root that makes the element 0. This function allows for `a`, `b`, and the
+    output of `func` to be of any broadcastable shapes.
+
+    Parameters
+    ----------
+    func : callable
+        The function whose root is desired. The signature must be::
+
+            func(x: ndarray, *args) -> ndarray
+
+         where each element of ``x`` is a finite real and ``args`` is a tuple,
+         which may contain an arbitrary number of components of any type(s).
+         ``func`` must be an elementwise function: each element ``func(x)[i]``
+         must equal ``func(x[i])`` for all indices ``i``. `_chandrupatla`
+         seeks an array ``x`` such that ``func(x)`` is an array of zeros.
+    a, b : array_like
+        The lower and upper bounds of the root of the function. Must be
+        broadcastable with one another.
+    args : tuple, optional
+        Additional positional arguments to be passed to `func`.
+    xatol, xrtol, fatol, frtol : float, optional
+        Absolute and relative tolerances on the root and function value.
+        See Notes for details.
+    maxiter : int, optional
+        The maximum number of iterations of the algorithm to perform.
+        The default is the maximum possible number of bisections within
+        the (normal) floating point numbers of the relevant dtype.
+    callback : callable, optional
+        An optional user-supplied function to be called before the first
+        iteration and after each iteration.
+        Called as ``callback(res)``, where ``res`` is a ``_RichResult``
+        similar to that returned by `_chandrupatla` (but containing the current
+        iterate's values of all variables). If `callback` raises a
+        ``StopIteration``, the algorithm will terminate immediately and
+        `_chandrupatla` will return a result.
+
+    Returns
+    -------
+    res : _RichResult
+        An instance of `scipy._lib._util._RichResult` with the following
+        attributes. The descriptions are written as though the values will be
+        scalars; however, if `func` returns an array, the outputs will be
+        arrays of the same shape.
+
+        x : float
+            The root of the function, if the algorithm terminated successfully.
+        nfev : int
+            The number of times the function was called to find the root.
+        nit : int
+            The number of iterations of Chandrupatla's algorithm performed.
+        status : int
+            An integer representing the exit status of the algorithm.
+            ``0`` : The algorithm converged to the specified tolerances.
+            ``-1`` : The algorithm encountered an invalid bracket.
+            ``-2`` : The maximum number of iterations was reached.
+            ``-3`` : A non-finite value was encountered.
+            ``-4`` : Iteration was terminated by `callback`.
+            ``1`` : The algorithm is proceeding normally (in `callback` only).
+        success : bool
+            ``True`` when the algorithm terminated successfully (status ``0``).
+        fun : float
+            The value of `func` evaluated at `x`.
+        xl, xr : float
+            The lower and upper ends of the bracket.
+        fl, fr : float
+            The function value at the lower and upper ends of the bracket.
+
+    Notes
+    -----
+    Implemented based on Chandrupatla's original paper [1]_.
+
+    If ``xl`` and ``xr`` are the left and right ends of the bracket,
+    ``xmin = xl if abs(func(xl)) <= abs(func(xr)) else xr``,
+    and ``fmin0 = min(func(a), func(b))``, then the algorithm is considered to
+    have converged when ``abs(xr - xl) < xatol + abs(xmin) * xrtol`` or
+    ``fun(xmin) <= fatol + abs(fmin0) * frtol``. This is equivalent to the
+    termination condition described in [1]_ with ``xrtol = 4e-10``,
+    ``xatol = 1e-5``, and ``fatol = frtol = 0``. The default values are
+    ``xatol = 4*tiny``, ``xrtol = 4*eps``, ``frtol = 0``, and ``fatol = tiny``,
+    where ``eps`` and ``tiny`` are the precision and smallest normal number
+    of the result ``dtype`` of function inputs and outputs.
+
+    References
+    ----------
+
+    .. [1] Chandrupatla, Tirupathi R.
+        "A new hybrid quadratic/bisection algorithm for finding the zero of a
+        nonlinear function without using derivatives".
+        Advances in Engineering Software, 28(3), 145-149.
+        https://doi.org/10.1016/s0965-9978(96)00051-8
+
+    See Also
+    --------
+    brentq, brenth, ridder, bisect, newton
+
+    Examples
+    --------
+    >>> from scipy import optimize
+    >>> def f(x, c):
+    ...     return x**3 - 2*x - c
+    >>> c = 5
+    >>> res = optimize._chandrupatla._chandrupatla(f, 0, 3, args=(c,))
+    >>> res.x
+    2.0945514818937463
+
+    >>> c = [3, 4, 5]
+    >>> res = optimize._chandrupatla._chandrupatla(f, 0, 3, args=(c,))
+    >>> res.x
+    array([1.8932892 , 2.        , 2.09455148])
+
+    """
+    res = _chandrupatla_iv(func, args, xatol, xrtol,
+                           fatol, frtol, maxiter, callback)
+    func, args, xatol, xrtol, fatol, frtol, maxiter, callback = res
+
+    # Initialization
+    temp = eim._initialize(func, (a, b), args)
+    func, xs, fs, args, shape, dtype, xp = temp
+    x1, x2 = xs
+    f1, f2 = fs
+    status = xp.full_like(x1, eim._EINPROGRESS,
+                          dtype=xp.int32)  # in progress
+    nit, nfev = 0, 2  # two function evaluations performed above
+    finfo = xp.finfo(dtype)
+    xatol = 4*finfo.smallest_normal if xatol is None else xatol
+    xrtol = 4*finfo.eps if xrtol is None else xrtol
+    fatol = finfo.smallest_normal if fatol is None else fatol
+    frtol = frtol * xp.minimum(xp.abs(f1), xp.abs(f2))
+    maxiter = (math.log2(finfo.max) - math.log2(finfo.smallest_normal)
+               if maxiter is None else maxiter)
+    work = _RichResult(x1=x1, f1=f1, x2=x2, f2=f2, x3=None, f3=None, t=0.5,
+                       xatol=xatol, xrtol=xrtol, fatol=fatol, frtol=frtol,
+                       nit=nit, nfev=nfev, status=status)
+    res_work_pairs = [('status', 'status'), ('x', 'xmin'), ('fun', 'fmin'),
+                      ('nit', 'nit'), ('nfev', 'nfev'), ('xl', 'x1'),
+                      ('fl', 'f1'), ('xr', 'x2'), ('fr', 'f2')]
+
+    def pre_func_eval(work):
+        # [1] Figure 1 (first box)
+        x = work.x1 + work.t * (work.x2 - work.x1)
+        return x
+
+    def post_func_eval(x, f, work):
+        # [1] Figure 1 (first diamond and boxes)
+        # Note: y/n are reversed in figure; compare to BASIC in appendix
+        work.x3, work.f3 = (xp.asarray(work.x2, copy=True),
+                            xp.asarray(work.f2, copy=True))
+        j = xp.sign(f) == xp.sign(work.f1)
+        nj = ~j
+        work.x3[j], work.f3[j] = work.x1[j], work.f1[j]
+        work.x2[nj], work.f2[nj] = work.x1[nj], work.f1[nj]
+        work.x1, work.f1 = x, f
+
+    def check_termination(work):
+        # [1] Figure 1 (second diamond)
+        # Check for all terminal conditions and record statuses.
+
+        # See [1] Section 4 (first two sentences)
+        i = xp.abs(work.f1) < xp.abs(work.f2)
+        work.xmin = xp.where(i, work.x1, work.x2)
+        work.fmin = xp.where(i, work.f1, work.f2)
+        stop = xp.zeros_like(work.x1, dtype=xp.bool)  # termination condition met
+
+        # If function value tolerance is met, report successful convergence,
+        # regardless of other conditions. Note that `frtol` has been redefined
+        # as `frtol = frtol * minimum(f1, f2)`, where `f1` and `f2` are the
+        # function evaluated at the original ends of the bracket.
+        i = xp.abs(work.fmin) <= work.fatol + work.frtol
+        work.status[i] = eim._ECONVERGED
+        stop[i] = True
+
+        # If the bracket is no longer valid, report failure (unless a function
+        # tolerance is met, as detected above).
+        i = (xp.sign(work.f1) == xp.sign(work.f2)) & ~stop
+        NaN = xp.asarray(xp.nan, dtype=work.xmin.dtype)
+        work.xmin[i], work.fmin[i], work.status[i] = NaN, NaN, eim._ESIGNERR
+        stop[i] = True
+
+        # If the abscissae are non-finite or either function value is NaN,
+        # report failure.
+        x_nonfinite = ~(xp.isfinite(work.x1) & xp.isfinite(work.x2))
+        f_nan = xp.isnan(work.f1) & xp.isnan(work.f2)
+        i = (x_nonfinite | f_nan) & ~stop
+        work.xmin[i], work.fmin[i], work.status[i] = NaN, NaN, eim._EVALUEERR
+        stop[i] = True
+
+        # This is the convergence criterion used in bisect. Chandrupatla's
+        # criterion is equivalent to this except with a factor of 4 on `xrtol`.
+        work.dx = xp.abs(work.x2 - work.x1)
+        work.tol = xp.abs(work.xmin) * work.xrtol + work.xatol
+        i = work.dx < work.tol
+        work.status[i] = eim._ECONVERGED
+        stop[i] = True
+
+        return stop
+
+    def post_termination_check(work):
+        # [1] Figure 1 (third diamond and boxes / Equation 1)
+        xi1 = (work.x1 - work.x2) / (work.x3 - work.x2)
+        with np.errstate(divide='ignore', invalid='ignore'):
+            phi1 = (work.f1 - work.f2) / (work.f3 - work.f2)
+        alpha = (work.x3 - work.x1) / (work.x2 - work.x1)
+        j = ((1 - xp.sqrt(1 - xi1)) < phi1) & (phi1 < xp.sqrt(xi1))
+
+        f1j, f2j, f3j, alphaj = work.f1[j], work.f2[j], work.f3[j], alpha[j]
+        t = xp.full_like(alpha, 0.5)
+        t[j] = (f1j / (f1j - f2j) * f3j / (f3j - f2j)
+                - alphaj * f1j / (f3j - f1j) * f2j / (f2j - f3j))
+
+        # [1] Figure 1 (last box; see also BASIC in appendix with comment
+        # "Adjust T Away from the Interval Boundary")
+        tl = 0.5 * work.tol / work.dx
+        work.t = xp.clip(t, tl, 1 - tl)
+
+    def customize_result(res, shape):
+        xl, xr, fl, fr = res['xl'], res['xr'], res['fl'], res['fr']
+        i = res['xl'] < res['xr']
+        res['xl'] = xp.where(i, xl, xr)
+        res['xr'] = xp.where(i, xr, xl)
+        res['fl'] = xp.where(i, fl, fr)
+        res['fr'] = xp.where(i, fr, fl)
+        return shape
+
+    return eim._loop(work, callback, shape, maxiter, func, args, dtype,
+                     pre_func_eval, post_func_eval, check_termination,
+                     post_termination_check, customize_result, res_work_pairs,
+                     xp=xp)
+
+
+def _chandrupatla_iv(func, args, xatol, xrtol,
+                     fatol, frtol, maxiter, callback):
+    # Input validation for `_chandrupatla`
+
+    if not callable(func):
+        raise ValueError('`func` must be callable.')
+
+    if not np.iterable(args):
+        args = (args,)
+
+    # tolerances are floats, not arrays; OK to use NumPy
+    tols = np.asarray([xatol if xatol is not None else 1,
+                       xrtol if xrtol is not None else 1,
+                       fatol if fatol is not None else 1,
+                       frtol if frtol is not None else 1])
+    if (not np.issubdtype(tols.dtype, np.number) or np.any(tols < 0)
+            or np.any(np.isnan(tols)) or tols.shape != (4,)):
+        raise ValueError('Tolerances must be non-negative scalars.')
+
+    if maxiter is not None:
+        maxiter_int = int(maxiter)
+        if maxiter != maxiter_int or maxiter < 0:
+            raise ValueError('`maxiter` must be a non-negative integer.')
+
+    if callback is not None and not callable(callback):
+        raise ValueError('`callback` must be callable.')
+
+    return func, args, xatol, xrtol, fatol, frtol, maxiter, callback
+
+
+def _chandrupatla_minimize(func, x1, x2, x3, *, args=(), xatol=None,
+                           xrtol=None, fatol=None, frtol=None, maxiter=100,
+                           callback=None):
+    """Find the minimizer of an elementwise function.
+
+    For each element of the output of `func`, `_chandrupatla_minimize` seeks
+    the scalar minimizer that minimizes the element. This function allows for
+    `x1`, `x2`, `x3`, and the elements of `args` to be arrays of any
+    broadcastable shapes.
+
+    Parameters
+    ----------
+    func : callable
+        The function whose minimizer is desired. The signature must be::
+
+            func(x: ndarray, *args) -> ndarray
+
+         where each element of ``x`` is a finite real and ``args`` is a tuple,
+         which may contain an arbitrary number of arrays that are broadcastable
+         with `x`. ``func`` must be an elementwise function: each element
+         ``func(x)[i]`` must equal ``func(x[i])`` for all indices ``i``.
+         `_chandrupatla` seeks an array ``x`` such that ``func(x)`` is an array
+         of minima.
+    x1, x2, x3 : array_like
+        The abscissae of a standard scalar minimization bracket. A bracket is
+        valid if ``x1 < x2 < x3`` and ``func(x1) > func(x2) <= func(x3)``.
+        Must be broadcastable with one another and `args`.
+    args : tuple, optional
+        Additional positional arguments to be passed to `func`.  Must be arrays
+        broadcastable with `x1`, `x2`, and `x3`. If the callable to be
+        differentiated requires arguments that are not broadcastable with `x`,
+        wrap that callable with `func` such that `func` accepts only `x` and
+        broadcastable arrays.
+    xatol, xrtol, fatol, frtol : float, optional
+        Absolute and relative tolerances on the minimizer and function value.
+        See Notes for details.
+    maxiter : int, optional
+        The maximum number of iterations of the algorithm to perform.
+    callback : callable, optional
+        An optional user-supplied function to be called before the first
+        iteration and after each iteration.
+        Called as ``callback(res)``, where ``res`` is a ``_RichResult``
+        similar to that returned by `_chandrupatla_minimize` (but containing
+        the current iterate's values of all variables). If `callback` raises a
+        ``StopIteration``, the algorithm will terminate immediately and
+        `_chandrupatla_minimize` will return a result.
+
+    Returns
+    -------
+    res : _RichResult
+        An instance of `scipy._lib._util._RichResult` with the following
+        attributes. (The descriptions are written as though the values will be
+        scalars; however, if `func` returns an array, the outputs will be
+        arrays of the same shape.)
+
+        success : bool
+            ``True`` when the algorithm terminated successfully (status ``0``).
+        status : int
+            An integer representing the exit status of the algorithm.
+            ``0`` : The algorithm converged to the specified tolerances.
+            ``-1`` : The algorithm encountered an invalid bracket.
+            ``-2`` : The maximum number of iterations was reached.
+            ``-3`` : A non-finite value was encountered.
+            ``-4`` : Iteration was terminated by `callback`.
+            ``1`` : The algorithm is proceeding normally (in `callback` only).
+        x : float
+            The minimizer of the function, if the algorithm terminated
+            successfully.
+        fun : float
+            The value of `func` evaluated at `x`.
+        nfev : int
+            The number of points at which `func` was evaluated.
+        nit : int
+            The number of iterations of the algorithm that were performed.
+        xl, xm, xr : float
+            The final three-point bracket.
+        fl, fm, fr : float
+            The function value at the bracket points.
+
+    Notes
+    -----
+    Implemented based on Chandrupatla's original paper [1]_.
+
+    If ``x1 < x2 < x3`` are the points of the bracket and ``f1 > f2 <= f3``
+    are the values of ``func`` at those points, then the algorithm is
+    considered to have converged when ``x3 - x1 <= abs(x2)*xrtol + xatol``
+    or ``(f1 - 2*f2 + f3)/2 <= abs(f2)*frtol + fatol``. Note that first of
+    these differs from the termination conditions described in [1]_. The
+    default values of `xrtol` is the square root of the precision of the
+    appropriate dtype, and ``xatol = fatol = frtol`` is the smallest normal
+    number of the appropriate dtype.
+
+    References
+    ----------
+    .. [1] Chandrupatla, Tirupathi R. (1998).
+        "An efficient quadratic fit-sectioning algorithm for minimization
+        without derivatives".
+        Computer Methods in Applied Mechanics and Engineering, 152 (1-2),
+        211-217. https://doi.org/10.1016/S0045-7825(97)00190-4
+
+    See Also
+    --------
+    golden, brent, bounded
+
+    Examples
+    --------
+    >>> from scipy.optimize._chandrupatla import _chandrupatla_minimize
+    >>> def f(x, args=1):
+    ...     return (x - args)**2
+    >>> res = _chandrupatla_minimize(f, -5, 0, 5)
+    >>> res.x
+    1.0
+    >>> c = [1, 1.5, 2]
+    >>> res = _chandrupatla_minimize(f, -5, 0, 5, args=(c,))
+    >>> res.x
+    array([1. , 1.5, 2. ])
+    """
+    res = _chandrupatla_iv(func, args, xatol, xrtol,
+                           fatol, frtol, maxiter, callback)
+    func, args, xatol, xrtol, fatol, frtol, maxiter, callback = res
+
+    # Initialization
+    xs = (x1, x2, x3)
+    temp = eim._initialize(func, xs, args)
+    func, xs, fs, args, shape, dtype, xp = temp  # line split for PEP8
+    x1, x2, x3 = xs
+    f1, f2, f3 = fs
+    phi = xp.asarray(0.5 + 0.5*5**0.5, dtype=dtype)[()]  # golden ratio
+    status = xp.full_like(x1, eim._EINPROGRESS, dtype=xp.int32)  # in progress
+    nit, nfev = 0, 3  # three function evaluations performed above
+    fatol = xp.finfo(dtype).smallest_normal if fatol is None else fatol
+    frtol = xp.finfo(dtype).smallest_normal if frtol is None else frtol
+    xatol = xp.finfo(dtype).smallest_normal if xatol is None else xatol
+    xrtol = math.sqrt(xp.finfo(dtype).eps) if xrtol is None else xrtol
+
+    # Ensure that x1 < x2 < x3 initially.
+    xs, fs = xp.stack((x1, x2, x3)), xp.stack((f1, f2, f3))
+    i = xp.argsort(xs, axis=0)
+    x1, x2, x3 = xp.take_along_axis(xs, i, axis=0)  # data-apis/array-api#808
+    f1, f2, f3 = xp.take_along_axis(fs, i, axis=0)  # data-apis/array-api#808
+    q0 = xp_copy(x3)  # "At the start, q0 is set at x3..." ([1] after (7))
+
+    work = _RichResult(x1=x1, f1=f1, x2=x2, f2=f2, x3=x3, f3=f3, phi=phi,
+                       xatol=xatol, xrtol=xrtol, fatol=fatol, frtol=frtol,
+                       nit=nit, nfev=nfev, status=status, q0=q0, args=args)
+    res_work_pairs = [('status', 'status'),
+                      ('x', 'x2'), ('fun', 'f2'),
+                      ('nit', 'nit'), ('nfev', 'nfev'),
+                      ('xl', 'x1'), ('xm', 'x2'), ('xr', 'x3'),
+                      ('fl', 'f1'), ('fm', 'f2'), ('fr', 'f3')]
+
+    def pre_func_eval(work):
+        # `_check_termination` is called first -> `x3 - x2 > x2 - x1`
+        # But let's calculate a few terms that we'll reuse
+        x21 = work.x2 - work.x1
+        x32 = work.x3 - work.x2
+
+        # [1] Section 3. "The quadratic minimum point Q1 is calculated using
+        # the relations developed in the previous section." [1] Section 2 (5/6)
+        A = x21 * (work.f3 - work.f2)
+        B = x32 * (work.f1 - work.f2)
+        C = A / (A + B)
+        # q1 = C * (work.x1 + work.x2) / 2 + (1 - C) * (work.x2 + work.x3) / 2
+        q1 = 0.5 * (C*(work.x1 - work.x3) + work.x2 + work.x3)  # much faster
+        # this is an array, so multiplying by 0.5 does not change dtype
+
+        # "If Q1 and Q0 are sufficiently close... Q1 is accepted if it is
+        # sufficiently away from the inside point x2"
+        i = xp.abs(q1 - work.q0) < 0.5 * xp.abs(x21)  # [1] (7)
+        xi = q1[i]
+        # Later, after (9), "If the point Q1 is in a +/- xtol neighborhood of
+        # x2, the new point is chosen in the larger interval at a distance
+        # tol away from x2."
+        # See also QBASIC code after "Accept Ql adjust if close to X2".
+        j = xp.abs(q1[i] - work.x2[i]) <= work.xtol[i]
+        xi[j] = work.x2[i][j] + xp.sign(x32[i][j]) * work.xtol[i][j]
+
+        # "If condition (7) is not satisfied, golden sectioning of the larger
+        # interval is carried out to introduce the new point."
+        # (For simplicity, we go ahead and calculate it for all points, but we
+        # change the elements for which the condition was satisfied.)
+        x = work.x2 + (2 - work.phi) * x32
+        x[i] = xi
+
+        # "We define Q0 as the value of Q1 at the previous iteration."
+        work.q0 = q1
+        return x
+
+    def post_func_eval(x, f, work):
+        # Standard logic for updating a three-point bracket based on a new
+        # point. In QBASIC code, see "IF SGN(X-X2) = SGN(X3-X2) THEN...".
+        # There is an awful lot of data copying going on here; this would
+        # probably benefit from code optimization or implementation in Pythran.
+        i = xp.sign(x - work.x2) == xp.sign(work.x3 - work.x2)
+        xi, x1i, x2i, x3i = x[i], work.x1[i], work.x2[i], work.x3[i],
+        fi, f1i, f2i, f3i = f[i], work.f1[i], work.f2[i], work.f3[i]
+        j = fi > f2i
+        x3i[j], f3i[j] = xi[j], fi[j]
+        j = ~j
+        x1i[j], f1i[j], x2i[j], f2i[j] = x2i[j], f2i[j], xi[j], fi[j]
+
+        ni = ~i
+        xni, x1ni, x2ni, x3ni = x[ni], work.x1[ni], work.x2[ni], work.x3[ni],
+        fni, f1ni, f2ni, f3ni = f[ni], work.f1[ni], work.f2[ni], work.f3[ni]
+        j = fni > f2ni
+        x1ni[j], f1ni[j] = xni[j], fni[j]
+        j = ~j
+        x3ni[j], f3ni[j], x2ni[j], f2ni[j] = x2ni[j], f2ni[j], xni[j], fni[j]
+
+        work.x1[i], work.x2[i], work.x3[i] = x1i, x2i, x3i
+        work.f1[i], work.f2[i], work.f3[i] = f1i, f2i, f3i
+        work.x1[ni], work.x2[ni], work.x3[ni] = x1ni, x2ni, x3ni,
+        work.f1[ni], work.f2[ni], work.f3[ni] = f1ni, f2ni, f3ni
+
+    def check_termination(work):
+        # Check for all terminal conditions and record statuses.
+        stop = xp.zeros_like(work.x1, dtype=bool)  # termination condition met
+
+        # Bracket is invalid; stop and don't return minimizer/minimum
+        i = ((work.f2 > work.f1) | (work.f2 > work.f3))
+        work.x2[i], work.f2[i] = xp.nan, xp.nan
+        stop[i], work.status[i] = True, eim._ESIGNERR
+
+        # Non-finite values; stop and don't return minimizer/minimum
+        finite = xp.isfinite(work.x1+work.x2+work.x3+work.f1+work.f2+work.f3)
+        i = ~(finite | stop)
+        work.x2[i], work.f2[i] = xp.nan, xp.nan
+        stop[i], work.status[i] = True, eim._EVALUEERR
+
+        # [1] Section 3 "Points 1 and 3 are interchanged if necessary to make
+        # the (x2, x3) the larger interval."
+        # Note: I had used np.choose; this is much faster. This would be a good
+        # place to save e.g. `work.x3 - work.x2` for reuse, but I tried and
+        # didn't notice a speed boost, so let's keep it simple.
+        i = xp.abs(work.x3 - work.x2) < xp.abs(work.x2 - work.x1)
+        temp = work.x1[i]
+        work.x1[i] = work.x3[i]
+        work.x3[i] = temp
+        temp = work.f1[i]
+        work.f1[i] = work.f3[i]
+        work.f3[i] = temp
+
+        # [1] Section 3 (bottom of page 212)
+        # "We set a tolerance value xtol..."
+        work.xtol = xp.abs(work.x2) * work.xrtol + work.xatol  # [1] (8)
+        # "The convergence based on interval is achieved when..."
+        # Note: Equality allowed in case of `xtol=0`
+        i = xp.abs(work.x3 - work.x2) <= 2 * work.xtol  # [1] (9)
+
+        # "We define ftol using..."
+        ftol = xp.abs(work.f2) * work.frtol + work.fatol  # [1] (10)
+        # "The convergence based on function values is achieved when..."
+        # Note 1: modify in place to incorporate tolerance on function value.
+        # Note 2: factor of 2 is not in the text; see QBASIC start of DO loop
+        i |= (work.f1 - 2 * work.f2 + work.f3) <= 2*ftol  # [1] (11)
+        i &= ~stop
+        stop[i], work.status[i] = True, eim._ECONVERGED
+
+        return stop
+
+    def post_termination_check(work):
+        pass
+
+    def customize_result(res, shape):
+        xl, xr, fl, fr = res['xl'], res['xr'], res['fl'], res['fr']
+        i = res['xl'] >= res['xr']
+        res['xl'] = xp.where(i, xr, xl)
+        res['xr'] = xp.where(i, xl, xr)
+        res['fl'] = xp.where(i, fr, fl)
+        res['fr'] = xp.where(i, fl, fr)
+        return shape
+
+    return eim._loop(work, callback, shape, maxiter, func, args, dtype,
+                     pre_func_eval, post_func_eval, check_termination,
+                     post_termination_check, customize_result, res_work_pairs,
+                     xp=xp)

venv/lib/python3.13/site-packages/scipy/optimize/_cobyla_py.py

@@ -0,0 +1,297 @@
+"""
+Interface to Constrained Optimization By Linear Approximation
+
+Functions
+---------
+.. autosummary::
+   :toctree: generated/
+
+    fmin_cobyla
+
+"""
+
+from inspect import signature
+
+import numpy as np
+from ._optimize import (OptimizeResult, _check_unknown_options,
+    _prepare_scalar_function)
+from ._constraints import NonlinearConstraint
+
+
+__all__ = ['fmin_cobyla']
+
+
+def fmin_cobyla(func, x0, cons, args=(), consargs=None, rhobeg=1.0,
+                rhoend=1e-4, maxfun=1000, disp=None, catol=2e-4,
+                *, callback=None):
+    """
+    Minimize a function using the Constrained Optimization By Linear
+    Approximation (COBYLA) method. This method uses the pure-python implementation
+    of the algorithm from PRIMA.
+
+    Parameters
+    ----------
+    func : callable
+        Function to minimize. In the form func(x, \\*args).
+    x0 : ndarray
+        Initial guess.
+    cons : sequence
+        Constraint functions; must all be ``>=0`` (a single function
+        if only 1 constraint). Each function takes the parameters `x`
+        as its first argument, and it can return either a single number or
+        an array or list of numbers.
+    args : tuple, optional
+        Extra arguments to pass to function.
+    consargs : tuple, optional
+        Extra arguments to pass to constraint functions (default of None means
+        use same extra arguments as those passed to func).
+        Use ``()`` for no extra arguments.
+    rhobeg : float, optional
+        Reasonable initial changes to the variables.
+    rhoend : float, optional
+        Final accuracy in the optimization (not precisely guaranteed). This
+        is a lower bound on the size of the trust region.
+    disp : {0, 1, 2, 3}, optional
+        Controls the frequency of output; 0 implies no output.
+    maxfun : int, optional
+        Maximum number of function evaluations.
+    catol : float, optional
+        Absolute tolerance for constraint violations.
+    callback : callable, optional
+        Called after each iteration, as ``callback(x)``, where ``x`` is the
+        current parameter vector.
+
+    Returns
+    -------
+    x : ndarray
+        The argument that minimises `f`.
+
+    See also
+    --------
+    minimize: Interface to minimization algorithms for multivariate
+        functions. See the 'COBYLA' `method` in particular.
+
+    Notes
+    -----
+    This algorithm is based on linear approximations to the objective
+    function and each constraint. We briefly describe the algorithm.
+
+    Suppose the function is being minimized over k variables. At the
+    jth iteration the algorithm has k+1 points v_1, ..., v_(k+1),
+    an approximate solution x_j, and a radius RHO_j.
+    (i.e., linear plus a constant) approximations to the objective
+    function and constraint functions such that their function values
+    agree with the linear approximation on the k+1 points v_1,.., v_(k+1).
+    This gives a linear program to solve (where the linear approximations
+    of the constraint functions are constrained to be non-negative).
+
+    However, the linear approximations are likely only good
+    approximations near the current simplex, so the linear program is
+    given the further requirement that the solution, which
+    will become x_(j+1), must be within RHO_j from x_j. RHO_j only
+    decreases, never increases. The initial RHO_j is rhobeg and the
+    final RHO_j is rhoend. In this way COBYLA's iterations behave
+    like a trust region algorithm.
+
+    Additionally, the linear program may be inconsistent, or the
+    approximation may give poor improvement. For details about
+    how these issues are resolved, as well as how the points v_i are
+    updated, refer to the source code or the references below.
+
+        .. versionchanged:: 1.16.0
+            The original Powell implementation was replaced by a pure
+            Python version from the PRIMA package, with bug fixes and
+            improvements being made.
+
+
+    References
+    ----------
+    Powell M.J.D. (1994), "A direct search optimization method that models
+    the objective and constraint functions by linear interpolation.", in
+    Advances in Optimization and Numerical Analysis, eds. S. Gomez and
+    J-P Hennart, Kluwer Academic (Dordrecht), pp. 51-67
+
+    Powell M.J.D. (1998), "Direct search algorithms for optimization
+    calculations", Acta Numerica 7, 287-336
+
+    Powell M.J.D. (2007), "A view of algorithms for optimization without
+    derivatives", Cambridge University Technical Report DAMTP 2007/NA03
+
+    Zhang Z. (2023), "PRIMA: Reference Implementation for Powell's Methods with
+    Modernization and Amelioration", https://www.libprima.net,
+    :doi:`10.5281/zenodo.8052654`
+
+    Examples
+    --------
+    Minimize the objective function f(x,y) = x*y subject
+    to the constraints x**2 + y**2 < 1 and y > 0::
+
+        >>> def objective(x):
+        ...     return x[0]*x[1]
+        ...
+        >>> def constr1(x):
+        ...     return 1 - (x[0]**2 + x[1]**2)
+        ...
+        >>> def constr2(x):
+        ...     return x[1]
+        ...
+        >>> from scipy.optimize import fmin_cobyla
+        >>> fmin_cobyla(objective, [0.0, 0.1], [constr1, constr2], rhoend=1e-7)
+        array([-0.70710685,  0.70710671])
+
+    The exact solution is (-sqrt(2)/2, sqrt(2)/2).
+
+
+
+    """
+    err = "cons must be a sequence of callable functions or a single"\
+          " callable function."
+    try:
+        len(cons)
+    except TypeError as e:
+        if callable(cons):
+            cons = [cons]
+        else:
+            raise TypeError(err) from e
+    else:
+        for thisfunc in cons:
+            if not callable(thisfunc):
+                raise TypeError(err)
+
+    if consargs is None:
+        consargs = args
+
+    # build constraints
+    nlcs = []
+    for con in cons:
+        # Use default argument, otherwise the last `con` is captured by all wrapped_con
+        def wrapped_con(x, confunc=con):
+            return confunc(x, *consargs)
+        nlcs.append(NonlinearConstraint(wrapped_con, 0, np.inf))
+
+    # options
+    opts = {'rhobeg': rhobeg,
+            'tol': rhoend,
+            'disp': disp,
+            'maxiter': maxfun,
+            'catol': catol,
+            'callback': callback}
+
+    sol = _minimize_cobyla(func, x0, args, constraints=nlcs,
+                           **opts)
+    if disp and not sol['success']:
+        print(f"COBYLA failed to find a solution: {sol.message}")
+    return sol['x']
+
+
+def _minimize_cobyla(fun, x0, args=(), constraints=(),
+                     rhobeg=1.0, tol=1e-4, maxiter=1000,
+                     disp=0, catol=None, f_target=-np.inf,
+                     callback=None, bounds=None, **unknown_options):
+    """
+    Minimize a scalar function of one or more variables using the
+    Constrained Optimization BY Linear Approximation (COBYLA) algorithm.
+    This method uses the pure-python implementation of the algorithm from PRIMA.
+
+    Options
+    -------
+    rhobeg : float
+        Reasonable initial changes to the variables.
+    tol : float
+        Final accuracy in the optimization (not precisely guaranteed).
+        This is a lower bound on the size of the trust region.
+    disp : int
+        Controls the frequency of output:
+            0. (default) There will be no printing
+            1. A message will be printed to the screen at the end of iteration, showing
+               the best vector of variables found and its objective function value
+            2. in addition to 1, each new value of RHO is printed to the screen,
+               with the best vector of variables so far and its objective function
+               value.
+            3. in addition to 2, each function evaluation with its variables will
+               be printed to the screen.
+    maxiter : int
+        Maximum number of function evaluations.
+    catol : float
+        Tolerance (absolute) for constraint violations
+    f_target : float
+        Stop if the objective function is less than `f_target`.
+
+        .. versionchanged:: 1.16.0
+            The original Powell implementation was replaced by a pure
+            Python version from the PRIMA package, with bug fixes and
+            improvements being made.
+
+
+    References
+    ----------
+    Zhang Z. (2023), "PRIMA: Reference Implementation for Powell's Methods with
+    Modernization and Amelioration", https://www.libprima.net,
+    :doi:`10.5281/zenodo.8052654`
+    """
+    from .._lib.pyprima import minimize
+    from .._lib.pyprima.common.infos import SMALL_TR_RADIUS, FTARGET_ACHIEVED
+    from .._lib.pyprima.common.message import get_info_string
+    _check_unknown_options(unknown_options)
+    rhoend = tol
+    iprint = disp if disp is not None else 0
+    if iprint != 0 and iprint != 1 and iprint != 2 and iprint != 3:
+        raise ValueError(f'disp argument to minimize must be 0, 1, 2, or 3,\
+                          received {iprint}')
+
+    # create the ScalarFunction, cobyla doesn't require derivative function
+    def _jac(x, *args):
+        return None
+
+    sf = _prepare_scalar_function(fun, x0, args=args, jac=_jac)
+
+    if callback is not None:
+        sig = signature(callback)
+        if set(sig.parameters) == {"intermediate_result"}:
+            def wrapped_callback_intermediate(x, f, nf, tr, cstrv, nlconstrlist):
+                intermediate_result = OptimizeResult(x=np.copy(x), fun=f, nfev=nf,
+                                                     nit=tr, maxcv=cstrv)
+                callback(intermediate_result=intermediate_result)
+        else:
+            def wrapped_callback_intermediate(x, f, nf, tr, cstrv, nlconstrlist):
+                callback(np.copy(x))
+        def wrapped_callback(x, f, nf, tr, cstrv, nlconstrlist):
+            try:
+                wrapped_callback_intermediate(x, f, nf, tr, cstrv, nlconstrlist)
+                return False
+            except StopIteration:
+                return True
+    else:
+        wrapped_callback = None
+
+
+    ctol = catol if catol is not None else np.sqrt(np.finfo(float).eps)
+    options = {
+        'rhobeg': rhobeg,
+        'rhoend': rhoend,
+        'maxfev': maxiter,
+        'iprint': iprint,
+        'ctol': ctol,
+        'ftarget': f_target,
+    }
+
+    result = minimize(sf.fun, x0, method='cobyla', bounds=bounds,
+                      constraints=constraints, callback=wrapped_callback,
+                      options=options)
+
+
+    if result.cstrv > ctol:
+        success = False
+        message = ('Did not converge to a solution satisfying the constraints. See '
+                  '`maxcv` for the magnitude of the violation.')
+    else:
+        success = result.info == SMALL_TR_RADIUS or result.info == FTARGET_ACHIEVED
+        message = get_info_string('COBYLA', result.info)
+
+    return OptimizeResult(x=result.x,
+                          status=result.info,
+                          success=success,
+                          message=message,
+                          nfev=result.nf,
+                          fun=result.f,
+                          maxcv=result.cstrv)

venv/lib/python3.13/site-packages/scipy/optimize/_cobyqa_py.py

@@ -0,0 +1,72 @@
+import numpy as np
+from threading import Lock
+
+from ._optimize import _check_unknown_options
+
+
+COBYQA_LOCK = Lock()
+
+
+def _minimize_cobyqa(fun, x0, args=(), bounds=None, constraints=(),
+                     callback=None, disp=False, maxfev=None, maxiter=None,
+                     f_target=-np.inf, feasibility_tol=1e-8,
+                     initial_tr_radius=1.0, final_tr_radius=1e-6, scale=False,
+                     **unknown_options):
+    """
+    Minimize a scalar function of one or more variables using the
+    Constrained Optimization BY Quadratic Approximations (COBYQA) algorithm [1]_.
+
+    .. versionadded:: 1.14.0
+
+    Options
+    -------
+    disp : bool
+        Set to True to print information about the optimization procedure.
+        Default is ``False``.
+    maxfev : int
+        Maximum number of function evaluations. Default is ``500 * n``, where
+        ``n`` is the number of variables.
+    maxiter : int
+        Maximum number of iterations. Default is ``1000 * n``, where ``n`` is
+        the number of variables.
+    f_target : float
+        Target value for the objective function. The optimization procedure is
+        terminated when the objective function value of a feasible point (see
+        `feasibility_tol` below) is less than or equal to this target. Default
+        is ``-numpy.inf``.
+    feasibility_tol : float
+        Absolute tolerance for the constraint violation. Default is ``1e-8``.
+    initial_tr_radius : float
+        Initial trust-region radius. Typically, this value should be in the
+        order of one tenth of the greatest expected change to the variables.
+        Default is ``1.0``.
+    final_tr_radius : float
+        Final trust-region radius. It should indicate the accuracy required in
+        the final values of the variables. If provided, this option overrides
+        the value of `tol` in the `minimize` function. Default is ``1e-6``.
+    scale : bool
+        Set to True to scale the variables according to the bounds. If True and
+        if all the lower and upper bounds are finite, the variables are scaled
+        to be within the range :math:`[-1, 1]`. If any of the lower or upper
+        bounds is infinite, the variables are not scaled. Default is ``False``.
+
+    References
+    ----------
+    .. [1] COBYQA
+           https://www.cobyqa.com/stable/
+    """
+    from .._lib.cobyqa import minimize  # import here to avoid circular imports
+
+    _check_unknown_options(unknown_options)
+    options = {
+        'disp': bool(disp),
+        'maxfev': int(maxfev) if maxfev is not None else 500 * len(x0),
+        'maxiter': int(maxiter) if maxiter is not None else 1000 * len(x0),
+        'target': float(f_target),
+        'feasibility_tol': float(feasibility_tol),
+        'radius_init': float(initial_tr_radius),
+        'radius_final': float(final_tr_radius),
+        'scale': bool(scale),
+    }
+    with COBYQA_LOCK:
+        return minimize(fun, x0, args, bounds, constraints, callback, options)

venv/lib/python3.13/site-packages/scipy/optimize/_constraints.py

@@ -0,0 +1,598 @@
+"""Constraints definition for minimize."""
+from warnings import warn, catch_warnings, simplefilter, filterwarnings
+
+import numpy as np
+
+from ._differentiable_functions import (
+    VectorFunction, LinearVectorFunction, IdentityVectorFunction
+)
+from ._hessian_update_strategy import BFGS
+from ._optimize import OptimizeWarning
+
+from scipy._lib._sparse import issparse
+
+
+def _arr_to_scalar(x):
+    # If x is a numpy array, return x.item().  This will
+    # fail if the array has more than one element.
+    return x.item() if isinstance(x, np.ndarray) else x
+
+
+class NonlinearConstraint:
+    """Nonlinear constraint on the variables.
+
+    The constraint has the general inequality form::
+
+        lb <= fun(x) <= ub
+
+    Here the vector of independent variables x is passed as ndarray of shape
+    (n,) and ``fun`` returns a vector with m components.
+
+    It is possible to use equal bounds to represent an equality constraint or
+    infinite bounds to represent a one-sided constraint.
+
+    Parameters
+    ----------
+    fun : callable
+        The function defining the constraint.
+        The signature is ``fun(x) -> array_like, shape (m,)``.
+    lb, ub : array_like
+        Lower and upper bounds on the constraint. Each array must have the
+        shape (m,) or be a scalar, in the latter case a bound will be the same
+        for all components of the constraint. Use ``np.inf`` with an
+        appropriate sign to specify a one-sided constraint.
+        Set components of `lb` and `ub` equal to represent an equality
+        constraint. Note that you can mix constraints of different types:
+        interval, one-sided or equality, by setting different components of
+        `lb` and `ub` as  necessary.
+    jac : {callable,  '2-point', '3-point', 'cs'}, optional
+        Method of computing the Jacobian matrix (an m-by-n matrix,
+        where element (i, j) is the partial derivative of f[i] with
+        respect to x[j]).  The keywords {'2-point', '3-point',
+        'cs'} select a finite difference scheme for the numerical estimation.
+        A callable must have the following signature::
+
+            jac(x) -> {ndarray, sparse array}, shape (m, n)
+
+        Default is '2-point'.
+    hess : {callable, '2-point', '3-point', 'cs', HessianUpdateStrategy, None}, optional
+        Method for computing the Hessian matrix. The keywords
+        {'2-point', '3-point', 'cs'} select a finite difference scheme for
+        numerical  estimation.  Alternatively, objects implementing
+        `HessianUpdateStrategy` interface can be used to approximate the
+        Hessian. Currently available implementations are:
+
+        - `BFGS` (default option)
+        - `SR1`
+
+        A callable must return the Hessian matrix of ``dot(fun, v)`` and
+        must have the following signature:
+        ``hess(x, v) -> {LinearOperator, sparse array, array_like}, shape (n, n)``.
+        Here ``v`` is ndarray with shape (m,) containing Lagrange multipliers.
+    keep_feasible : array_like of bool, optional
+        Whether to keep the constraint components feasible throughout
+        iterations. A single value set this property for all components.
+        Default is False. Has no effect for equality constraints.
+    finite_diff_rel_step: None or array_like, optional
+        Relative step size for the finite difference approximation. Default is
+        None, which will select a reasonable value automatically depending
+        on a finite difference scheme.
+    finite_diff_jac_sparsity: {None, array_like, sparse array}, optional
+        Defines the sparsity structure of the Jacobian matrix for finite
+        difference estimation, its shape must be (m, n). If the Jacobian has
+        only few non-zero elements in *each* row, providing the sparsity
+        structure will greatly speed up the computations. A zero entry means
+        that a corresponding element in the Jacobian is identically zero.
+        If provided, forces the use of 'lsmr' trust-region solver.
+        If None (default) then dense differencing will be used.
+
+    Notes
+    -----
+    Finite difference schemes {'2-point', '3-point', 'cs'} may be used for
+    approximating either the Jacobian or the Hessian. We, however, do not allow
+    its use for approximating both simultaneously. Hence whenever the Jacobian
+    is estimated via finite-differences, we require the Hessian to be estimated
+    using one of the quasi-Newton strategies.
+
+    The scheme 'cs' is potentially the most accurate, but requires the function
+    to correctly handles complex inputs and be analytically continuable to the
+    complex plane. The scheme '3-point' is more accurate than '2-point' but
+    requires twice as many operations.
+
+    Examples
+    --------
+    Constrain ``x[0] < sin(x[1]) + 1.9``
+
+    >>> from scipy.optimize import NonlinearConstraint
+    >>> import numpy as np
+    >>> con = lambda x: x[0] - np.sin(x[1])
+    >>> nlc = NonlinearConstraint(con, -np.inf, 1.9)
+
+    """
+    def __init__(self, fun, lb, ub, jac='2-point', hess=None,
+                 keep_feasible=False, finite_diff_rel_step=None,
+                 finite_diff_jac_sparsity=None):
+        if hess is None:
+            hess = BFGS()
+        self.fun = fun
+        self.lb = lb
+        self.ub = ub
+        self.finite_diff_rel_step = finite_diff_rel_step
+        self.finite_diff_jac_sparsity = finite_diff_jac_sparsity
+        self.jac = jac
+        self.hess = hess
+        self.keep_feasible = keep_feasible
+
+
+class LinearConstraint:
+    """Linear constraint on the variables.
+
+    The constraint has the general inequality form::
+
+        lb <= A.dot(x) <= ub
+
+    Here the vector of independent variables x is passed as ndarray of shape
+    (n,) and the matrix A has shape (m, n).
+
+    It is possible to use equal bounds to represent an equality constraint or
+    infinite bounds to represent a one-sided constraint.
+
+    Parameters
+    ----------
+    A : {array_like, sparse array}, shape (m, n)
+        Matrix defining the constraint.
+    lb, ub : dense array_like, optional
+        Lower and upper limits on the constraint. Each array must have the
+        shape (m,) or be a scalar, in the latter case a bound will be the same
+        for all components of the constraint. Use ``np.inf`` with an
+        appropriate sign to specify a one-sided constraint.
+        Set components of `lb` and `ub` equal to represent an equality
+        constraint. Note that you can mix constraints of different types:
+        interval, one-sided or equality, by setting different components of
+        `lb` and `ub` as  necessary. Defaults to ``lb = -np.inf``
+        and ``ub = np.inf`` (no limits).
+    keep_feasible : dense array_like of bool, optional
+        Whether to keep the constraint components feasible throughout
+        iterations. A single value set this property for all components.
+        Default is False. Has no effect for equality constraints.
+    """
+    def _input_validation(self):
+        if self.A.ndim != 2:
+            message = "`A` must have exactly two dimensions."
+            raise ValueError(message)
+
+        try:
+            shape = self.A.shape[0:1]
+            self.lb = np.broadcast_to(self.lb, shape)
+            self.ub = np.broadcast_to(self.ub, shape)
+            self.keep_feasible = np.broadcast_to(self.keep_feasible, shape)
+        except ValueError:
+            message = ("`lb`, `ub`, and `keep_feasible` must be broadcastable "
+                       "to shape `A.shape[0:1]`")
+            raise ValueError(message)
+
+    def __init__(self, A, lb=-np.inf, ub=np.inf, keep_feasible=False):
+        if not issparse(A):
+            # In some cases, if the constraint is not valid, this emits a
+            # VisibleDeprecationWarning about ragged nested sequences
+            # before eventually causing an error. `scipy.optimize.milp` would
+            # prefer that this just error out immediately so it can handle it
+            # rather than concerning the user.
+            with catch_warnings():
+                simplefilter("error")
+                self.A = np.atleast_2d(A).astype(np.float64)
+        else:
+            self.A = A
+        if issparse(lb) or issparse(ub):
+            raise ValueError("Constraint limits must be dense arrays.")
+        self.lb = np.atleast_1d(lb).astype(np.float64)
+        self.ub = np.atleast_1d(ub).astype(np.float64)
+
+        if issparse(keep_feasible):
+            raise ValueError("`keep_feasible` must be a dense array.")
+        self.keep_feasible = np.atleast_1d(keep_feasible).astype(bool)
+        self._input_validation()
+
+    def residual(self, x):
+        """
+        Calculate the residual between the constraint function and the limits
+
+        For a linear constraint of the form::
+
+            lb <= A@x <= ub
+
+        the lower and upper residuals between ``A@x`` and the limits are values
+        ``sl`` and ``sb`` such that::
+
+            lb + sl == A@x == ub - sb
+
+        When all elements of ``sl`` and ``sb`` are positive, all elements of
+        the constraint are satisfied; a negative element in ``sl`` or ``sb``
+        indicates that the corresponding element of the constraint is not
+        satisfied.
+
+        Parameters
+        ----------
+        x: array_like
+            Vector of independent variables
+
+        Returns
+        -------
+        sl, sb : array-like
+            The lower and upper residuals
+        """
+        return self.A@x - self.lb, self.ub - self.A@x
+
+
+class Bounds:
+    """Bounds constraint on the variables.
+
+    The constraint has the general inequality form::
+
+        lb <= x <= ub
+
+    It is possible to use equal bounds to represent an equality constraint or
+    infinite bounds to represent a one-sided constraint.
+
+    Parameters
+    ----------
+    lb, ub : dense array_like, optional
+        Lower and upper bounds on independent variables. `lb`, `ub`, and
+        `keep_feasible` must be the same shape or broadcastable.
+        Set components of `lb` and `ub` equal
+        to fix a variable. Use ``np.inf`` with an appropriate sign to disable
+        bounds on all or some variables. Note that you can mix constraints of
+        different types: interval, one-sided or equality, by setting different
+        components of `lb` and `ub` as necessary. Defaults to ``lb = -np.inf``
+        and ``ub = np.inf`` (no bounds).
+    keep_feasible : dense array_like of bool, optional
+        Whether to keep the constraint components feasible throughout
+        iterations. Must be broadcastable with `lb` and `ub`.
+        Default is False. Has no effect for equality constraints.
+    """
+    def _input_validation(self):
+        try:
+            res = np.broadcast_arrays(self.lb, self.ub, self.keep_feasible)
+            self.lb, self.ub, self.keep_feasible = res
+        except ValueError:
+            message = "`lb`, `ub`, and `keep_feasible` must be broadcastable."
+            raise ValueError(message)
+
+    def __init__(self, lb=-np.inf, ub=np.inf, keep_feasible=False):
+        if issparse(lb) or issparse(ub):
+            raise ValueError("Lower and upper bounds must be dense arrays.")
+        self.lb = np.atleast_1d(lb)
+        self.ub = np.atleast_1d(ub)
+
+        if issparse(keep_feasible):
+            raise ValueError("`keep_feasible` must be a dense array.")
+        self.keep_feasible = np.atleast_1d(keep_feasible).astype(bool)
+        self._input_validation()
+
+    def __repr__(self):
+        start = f"{type(self).__name__}({self.lb!r}, {self.ub!r}"
+        if np.any(self.keep_feasible):
+            end = f", keep_feasible={self.keep_feasible!r})"
+        else:
+            end = ")"
+        return start + end
+
+    def residual(self, x):
+        """Calculate the residual (slack) between the input and the bounds
+
+        For a bound constraint of the form::
+
+            lb <= x <= ub
+
+        the lower and upper residuals between `x` and the bounds are values
+        ``sl`` and ``sb`` such that::
+
+            lb + sl == x == ub - sb
+
+        When all elements of ``sl`` and ``sb`` are positive, all elements of
+        ``x`` lie within the bounds; a negative element in ``sl`` or ``sb``
+        indicates that the corresponding element of ``x`` is out of bounds.
+
+        Parameters
+        ----------
+        x: array_like
+            Vector of independent variables
+
+        Returns
+        -------
+        sl, sb : array-like
+            The lower and upper residuals
+        """
+        return x - self.lb, self.ub - x
+
+
+class PreparedConstraint:
+    """Constraint prepared from a user defined constraint.
+
+    On creation it will check whether a constraint definition is valid and
+    the initial point is feasible. If created successfully, it will contain
+    the attributes listed below.
+
+    Parameters
+    ----------
+    constraint : {NonlinearConstraint, LinearConstraint`, Bounds}
+        Constraint to check and prepare.
+    x0 : array_like
+        Initial vector of independent variables.
+    sparse_jacobian : bool or None, optional
+        If bool, then the Jacobian of the constraint will be converted
+        to the corresponded format if necessary. If None (default), such
+        conversion is not made.
+    finite_diff_bounds : 2-tuple, optional
+        Lower and upper bounds on the independent variables for the finite
+        difference approximation, if applicable. Defaults to no bounds.
+
+    Attributes
+    ----------
+    fun : {VectorFunction, LinearVectorFunction, IdentityVectorFunction}
+        Function defining the constraint wrapped by one of the convenience
+        classes.
+    bounds : 2-tuple
+        Contains lower and upper bounds for the constraints --- lb and ub.
+        These are converted to ndarray and have a size equal to the number of
+        the constraints.
+    keep_feasible : ndarray
+         Array indicating which components must be kept feasible with a size
+         equal to the number of the constraints.
+    """
+    def __init__(self, constraint, x0, sparse_jacobian=None,
+                 finite_diff_bounds=(-np.inf, np.inf)):
+        if isinstance(constraint, NonlinearConstraint):
+            fun = VectorFunction(constraint.fun, x0,
+                                 constraint.jac, constraint.hess,
+                                 constraint.finite_diff_rel_step,
+                                 constraint.finite_diff_jac_sparsity,
+                                 finite_diff_bounds, sparse_jacobian)
+        elif isinstance(constraint, LinearConstraint):
+            fun = LinearVectorFunction(constraint.A, x0, sparse_jacobian)
+        elif isinstance(constraint, Bounds):
+            fun = IdentityVectorFunction(x0, sparse_jacobian)
+        else:
+            raise ValueError("`constraint` of an unknown type is passed.")
+
+        m = fun.m
+
+        lb = np.asarray(constraint.lb, dtype=float)
+        ub = np.asarray(constraint.ub, dtype=float)
+        keep_feasible = np.asarray(constraint.keep_feasible, dtype=bool)
+
+        lb = np.broadcast_to(lb, m)
+        ub = np.broadcast_to(ub, m)
+        keep_feasible = np.broadcast_to(keep_feasible, m)
+
+        if keep_feasible.shape != (m,):
+            raise ValueError("`keep_feasible` has a wrong shape.")
+
+        mask = keep_feasible & (lb != ub)
+        f0 = fun.f
+        if np.any(f0[mask] < lb[mask]) or np.any(f0[mask] > ub[mask]):
+            raise ValueError("`x0` is infeasible with respect to some "
+                             "inequality constraint with `keep_feasible` "
+                             "set to True.")
+
+        self.fun = fun
+        self.bounds = (lb, ub)
+        self.keep_feasible = keep_feasible
+
+    def violation(self, x):
+        """How much the constraint is exceeded by.
+
+        Parameters
+        ----------
+        x : array-like
+            Vector of independent variables
+
+        Returns
+        -------
+        excess : array-like
+            How much the constraint is exceeded by, for each of the
+            constraints specified by `PreparedConstraint.fun`.
+        """
+        with catch_warnings():
+            # Ignore the following warning, it's not important when
+            # figuring out total violation
+            # UserWarning: delta_grad == 0.0. Check if the approximated
+            # function is linear
+            filterwarnings("ignore", "delta_grad", UserWarning)
+            ev = self.fun.fun(np.asarray(x))
+
+        excess_lb = np.maximum(self.bounds[0] - ev, 0)
+        excess_ub = np.maximum(ev - self.bounds[1], 0)
+
+        return excess_lb + excess_ub
+
+
+def new_bounds_to_old(lb, ub, n):
+    """Convert the new bounds representation to the old one.
+
+    The new representation is a tuple (lb, ub) and the old one is a list
+    containing n tuples, ith containing lower and upper bound on a ith
+    variable.
+    If any of the entries in lb/ub are -np.inf/np.inf they are replaced by
+    None.
+    """
+    lb = np.broadcast_to(lb, n)
+    ub = np.broadcast_to(ub, n)
+
+    lb = [float(x) if x > -np.inf else None for x in lb]
+    ub = [float(x) if x < np.inf else None for x in ub]
+
+    return list(zip(lb, ub))
+
+
+def old_bound_to_new(bounds):
+    """Convert the old bounds representation to the new one.
+
+    The new representation is a tuple (lb, ub) and the old one is a list
+    containing n tuples, ith containing lower and upper bound on a ith
+    variable.
+    If any of the entries in lb/ub are None they are replaced by
+    -np.inf/np.inf.
+    """
+    lb, ub = zip(*bounds)
+
+    # Convert occurrences of None to -inf or inf, and replace occurrences of
+    # any numpy array x with x.item(). Then wrap the results in numpy arrays.
+    lb = np.array([float(_arr_to_scalar(x)) if x is not None else -np.inf
+                   for x in lb])
+    ub = np.array([float(_arr_to_scalar(x)) if x is not None else np.inf
+                   for x in ub])
+
+    return lb, ub
+
+
+def strict_bounds(lb, ub, keep_feasible, n_vars):
+    """Remove bounds which are not asked to be kept feasible."""
+    strict_lb = np.resize(lb, n_vars).astype(float)
+    strict_ub = np.resize(ub, n_vars).astype(float)
+    keep_feasible = np.resize(keep_feasible, n_vars)
+    strict_lb[~keep_feasible] = -np.inf
+    strict_ub[~keep_feasible] = np.inf
+    return strict_lb, strict_ub
+
+
+def new_constraint_to_old(con, x0):
+    """
+    Converts new-style constraint objects to old-style constraint dictionaries.
+    """
+    if isinstance(con, NonlinearConstraint):
+        if (con.finite_diff_jac_sparsity is not None or
+                con.finite_diff_rel_step is not None or
+                not isinstance(con.hess, BFGS) or  # misses user specified BFGS
+                con.keep_feasible):
+            warn("Constraint options `finite_diff_jac_sparsity`, "
+                 "`finite_diff_rel_step`, `keep_feasible`, and `hess`"
+                 "are ignored by this method.",
+                 OptimizeWarning, stacklevel=3)
+
+        fun = con.fun
+        if callable(con.jac):
+            jac = con.jac
+        else:
+            jac = None
+
+    else:  # LinearConstraint
+        if np.any(con.keep_feasible):
+            warn("Constraint option `keep_feasible` is ignored by this method.",
+                 OptimizeWarning, stacklevel=3)
+
+        A = con.A
+        if issparse(A):
+            A = A.toarray()
+        def fun(x):
+            return np.dot(A, x)
+        def jac(x):
+            return A
+
+    # FIXME: when bugs in VectorFunction/LinearVectorFunction are worked out,
+    # use pcon.fun.fun and pcon.fun.jac. Until then, get fun/jac above.
+    pcon = PreparedConstraint(con, x0)
+    lb, ub = pcon.bounds
+
+    i_eq = lb == ub
+    i_bound_below = np.logical_xor(lb != -np.inf, i_eq)
+    i_bound_above = np.logical_xor(ub != np.inf, i_eq)
+    i_unbounded = np.logical_and(lb == -np.inf, ub == np.inf)
+
+    if np.any(i_unbounded):
+        warn("At least one constraint is unbounded above and below. Such "
+             "constraints are ignored.",
+             OptimizeWarning, stacklevel=3)
+
+    ceq = []
+    if np.any(i_eq):
+        def f_eq(x):
+            y = np.array(fun(x)).flatten()
+            return y[i_eq] - lb[i_eq]
+        ceq = [{"type": "eq", "fun": f_eq}]
+
+        if jac is not None:
+            def j_eq(x):
+                dy = jac(x)
+                if issparse(dy):
+                    dy = dy.toarray()
+                dy = np.atleast_2d(dy)
+                return dy[i_eq, :]
+            ceq[0]["jac"] = j_eq
+
+    cineq = []
+    n_bound_below = np.sum(i_bound_below)
+    n_bound_above = np.sum(i_bound_above)
+    if n_bound_below + n_bound_above:
+        def f_ineq(x):
+            y = np.zeros(n_bound_below + n_bound_above)
+            y_all = np.array(fun(x)).flatten()
+            y[:n_bound_below] = y_all[i_bound_below] - lb[i_bound_below]
+            y[n_bound_below:] = -(y_all[i_bound_above] - ub[i_bound_above])
+            return y
+        cineq = [{"type": "ineq", "fun": f_ineq}]
+
+        if jac is not None:
+            def j_ineq(x):
+                dy = np.zeros((n_bound_below + n_bound_above, len(x0)))
+                dy_all = jac(x)
+                if issparse(dy_all):
+                    dy_all = dy_all.toarray()
+                dy_all = np.atleast_2d(dy_all)
+                dy[:n_bound_below, :] = dy_all[i_bound_below]
+                dy[n_bound_below:, :] = -dy_all[i_bound_above]
+                return dy
+            cineq[0]["jac"] = j_ineq
+
+    old_constraints = ceq + cineq
+
+    if len(old_constraints) > 1:
+        warn("Equality and inequality constraints are specified in the same "
+             "element of the constraint list. For efficient use with this "
+             "method, equality and inequality constraints should be specified "
+             "in separate elements of the constraint list. ",
+             OptimizeWarning, stacklevel=3)
+    return old_constraints
+
+
+def old_constraint_to_new(ic, con):
+    """
+    Converts old-style constraint dictionaries to new-style constraint objects.
+    """
+    # check type
+    try:
+        ctype = con['type'].lower()
+    except KeyError as e:
+        raise KeyError(f'Constraint {ic} has no type defined.') from e
+    except TypeError as e:
+        raise TypeError(
+            'Constraints must be a sequence of dictionaries.'
+        ) from e
+    except AttributeError as e:
+        raise TypeError("Constraint's type must be a string.") from e
+    else:
+        if ctype not in ['eq', 'ineq']:
+            raise ValueError(f"Unknown constraint type '{con['type']}'.")
+    if 'fun' not in con:
+        raise ValueError(f'Constraint {ic} has no function defined.')
+
+    lb = 0
+    if ctype == 'eq':
+        ub = 0
+    else:
+        ub = np.inf
+
+    jac = '2-point'
+    if 'args' in con:
+        args = con['args']
+        def fun(x):
+            return con["fun"](x, *args)
+        if 'jac' in con:
+            def jac(x):
+                return con["jac"](x, *args)
+    else:
+        fun = con['fun']
+        if 'jac' in con:
+            jac = con['jac']
+
+    return NonlinearConstraint(fun, lb, ub, jac)

venv/lib/python3.13/site-packages/scipy/optimize/_dcsrch.py

@@ -0,0 +1,728 @@
+import numpy as np
+
+"""
+# 2023 - ported from minpack2.dcsrch, dcstep (Fortran) to Python
+c     MINPACK-1 Project. June 1983.
+c     Argonne National Laboratory.
+c     Jorge J. More' and David J. Thuente.
+c
+c     MINPACK-2 Project. November 1993.
+c     Argonne National Laboratory and University of Minnesota.
+c     Brett M. Averick, Richard G. Carter, and Jorge J. More'.
+"""
+
+# NOTE this file was linted by black on first commit, and can be kept that way.
+
+
+class DCSRCH:
+    """
+    Parameters
+    ----------
+    phi : callable phi(alpha)
+        Function at point `alpha`
+    derphi : callable phi'(alpha)
+        Objective function derivative. Returns a scalar.
+    ftol : float
+        A nonnegative tolerance for the sufficient decrease condition.
+    gtol : float
+        A nonnegative tolerance for the curvature condition.
+    xtol : float
+        A nonnegative relative tolerance for an acceptable step. The
+        subroutine exits with a warning if the relative difference between
+        sty and stx is less than xtol.
+    stpmin : float
+        A nonnegative lower bound for the step.
+    stpmax :
+        A nonnegative upper bound for the step.
+
+    Notes
+    -----
+
+    This subroutine finds a step that satisfies a sufficient
+    decrease condition and a curvature condition.
+
+    Each call of the subroutine updates an interval with
+    endpoints stx and sty. The interval is initially chosen
+    so that it contains a minimizer of the modified function
+
+           psi(stp) = f(stp) - f(0) - ftol*stp*f'(0).
+
+    If psi(stp) <= 0 and f'(stp) >= 0 for some step, then the
+    interval is chosen so that it contains a minimizer of f.
+
+    The algorithm is designed to find a step that satisfies
+    the sufficient decrease condition
+
+           f(stp) <= f(0) + ftol*stp*f'(0),
+
+    and the curvature condition
+
+           abs(f'(stp)) <= gtol*abs(f'(0)).
+
+    If ftol is less than gtol and if, for example, the function
+    is bounded below, then there is always a step which satisfies
+    both conditions.
+
+    If no step can be found that satisfies both conditions, then
+    the algorithm stops with a warning. In this case stp only
+    satisfies the sufficient decrease condition.
+
+    A typical invocation of dcsrch has the following outline:
+
+    Evaluate the function at stp = 0.0d0; store in f.
+    Evaluate the gradient at stp = 0.0d0; store in g.
+    Choose a starting step stp.
+
+    task = 'START'
+    10 continue
+        call dcsrch(stp,f,g,ftol,gtol,xtol,task,stpmin,stpmax,
+                   isave,dsave)
+        if (task .eq. 'FG') then
+           Evaluate the function and the gradient at stp
+           go to 10
+           end if
+
+    NOTE: The user must not alter work arrays between calls.
+
+    The subroutine statement is
+
+        subroutine dcsrch(f,g,stp,ftol,gtol,xtol,stpmin,stpmax,
+                         task,isave,dsave)
+        where
+
+    stp is a double precision variable.
+        On entry stp is the current estimate of a satisfactory
+            step. On initial entry, a positive initial estimate
+            must be provided.
+        On exit stp is the current estimate of a satisfactory step
+            if task = 'FG'. If task = 'CONV' then stp satisfies
+            the sufficient decrease and curvature condition.
+
+    f is a double precision variable.
+        On initial entry f is the value of the function at 0.
+        On subsequent entries f is the value of the
+            function at stp.
+        On exit f is the value of the function at stp.
+
+    g is a double precision variable.
+        On initial entry g is the derivative of the function at 0.
+        On subsequent entries g is the derivative of the
+           function at stp.
+        On exit g is the derivative of the function at stp.
+
+    ftol is a double precision variable.
+        On entry ftol specifies a nonnegative tolerance for the
+           sufficient decrease condition.
+        On exit ftol is unchanged.
+
+    gtol is a double precision variable.
+        On entry gtol specifies a nonnegative tolerance for the
+           curvature condition.
+        On exit gtol is unchanged.
+
+    xtol is a double precision variable.
+        On entry xtol specifies a nonnegative relative tolerance
+          for an acceptable step. The subroutine exits with a
+          warning if the relative difference between sty and stx
+          is less than xtol.
+
+        On exit xtol is unchanged.
+
+    task is a character variable of length at least 60.
+        On initial entry task must be set to 'START'.
+        On exit task indicates the required action:
+
+           If task(1:2) = 'FG' then evaluate the function and
+           derivative at stp and call dcsrch again.
+
+           If task(1:4) = 'CONV' then the search is successful.
+
+           If task(1:4) = 'WARN' then the subroutine is not able
+           to satisfy the convergence conditions. The exit value of
+           stp contains the best point found during the search.
+
+          If task(1:5) = 'ERROR' then there is an error in the
+          input arguments.
+
+        On exit with convergence, a warning or an error, the
+           variable task contains additional information.
+
+    stpmin is a double precision variable.
+        On entry stpmin is a nonnegative lower bound for the step.
+        On exit stpmin is unchanged.
+
+    stpmax is a double precision variable.
+        On entry stpmax is a nonnegative upper bound for the step.
+        On exit stpmax is unchanged.
+
+    isave is an integer work array of dimension 2.
+
+    dsave is a double precision work array of dimension 13.
+
+    Subprograms called
+
+      MINPACK-2 ... dcstep
+    MINPACK-1 Project. June 1983.
+    Argonne National Laboratory.
+    Jorge J. More' and David J. Thuente.
+
+    MINPACK-2 Project. November 1993.
+    Argonne National Laboratory and University of Minnesota.
+    Brett M. Averick, Richard G. Carter, and Jorge J. More'.
+    """
+
+    def __init__(self, phi, derphi, ftol, gtol, xtol, stpmin, stpmax):
+        self.stage = None
+        self.ginit = None
+        self.gtest = None
+        self.gx = None
+        self.gy = None
+        self.finit = None
+        self.fx = None
+        self.fy = None
+        self.stx = None
+        self.sty = None
+        self.stmin = None
+        self.stmax = None
+        self.width = None
+        self.width1 = None
+
+        # leave all assessment of tolerances/limits to the first call of
+        # this object
+        self.ftol = ftol
+        self.gtol = gtol
+        self.xtol = xtol
+        self.stpmin = stpmin
+        self.stpmax = stpmax
+
+        self.phi = phi
+        self.derphi = derphi
+
+    def __call__(self, alpha1, phi0=None, derphi0=None, maxiter=100):
+        """
+        Parameters
+        ----------
+        alpha1 : float
+            alpha1 is the current estimate of a satisfactory
+            step. A positive initial estimate must be provided.
+        phi0 : float
+            the value of `phi` at 0 (if known).
+        derphi0 : float
+            the derivative of `derphi` at 0 (if known).
+        maxiter : int
+
+        Returns
+        -------
+        alpha : float
+            Step size, or None if no suitable step was found.
+        phi : float
+            Value of `phi` at the new point `alpha`.
+        phi0 : float
+            Value of `phi` at `alpha=0`.
+        task : bytes
+            On exit task indicates status information.
+
+           If task[:4] == b'CONV' then the search is successful.
+
+           If task[:4] == b'WARN' then the subroutine is not able
+           to satisfy the convergence conditions. The exit value of
+           stp contains the best point found during the search.
+
+           If task[:5] == b'ERROR' then there is an error in the
+           input arguments.
+        """
+        if phi0 is None:
+            phi0 = self.phi(0.0)
+        if derphi0 is None:
+            derphi0 = self.derphi(0.0)
+
+        phi1 = phi0
+        derphi1 = derphi0
+
+        task = b"START"
+        for i in range(maxiter):
+            stp, phi1, derphi1, task = self._iterate(
+                alpha1, phi1, derphi1, task
+            )
+
+            if not np.isfinite(stp):
+                task = b"WARN"
+                stp = None
+                break
+
+            if task[:2] == b"FG":
+                alpha1 = stp
+                phi1 = self.phi(stp)
+                derphi1 = self.derphi(stp)
+            else:
+                break
+        else:
+            # maxiter reached, the line search did not converge
+            stp = None
+            task = b"WARNING: dcsrch did not converge within max iterations"
+
+        if task[:5] == b"ERROR" or task[:4] == b"WARN":
+            stp = None  # failed
+
+        return stp, phi1, phi0, task
+
+    def _iterate(self, stp, f, g, task):
+        """
+        Parameters
+        ----------
+        stp : float
+            The current estimate of a satisfactory step. On initial entry, a
+            positive initial estimate must be provided.
+        f : float
+            On first call f is the value of the function at 0. On subsequent
+            entries f should be the value of the function at stp.
+        g : float
+            On initial entry g is the derivative of the function at 0. On
+            subsequent entries g is the derivative of the function at stp.
+        task : bytes
+            On initial entry task must be set to 'START'.
+
+        On exit with convergence, a warning or an error, the
+           variable task contains additional information.
+
+
+        Returns
+        -------
+        stp, f, g, task: tuple
+
+            stp : float
+                the current estimate of a satisfactory step if task = 'FG'. If
+                task = 'CONV' then stp satisfies the sufficient decrease and
+                curvature condition.
+            f : float
+                the value of the function at stp.
+            g : float
+                the derivative of the function at stp.
+            task : bytes
+                On exit task indicates the required action:
+
+               If task(1:2) == b'FG' then evaluate the function and
+               derivative at stp and call dcsrch again.
+
+               If task(1:4) == b'CONV' then the search is successful.
+
+               If task(1:4) == b'WARN' then the subroutine is not able
+               to satisfy the convergence conditions. The exit value of
+               stp contains the best point found during the search.
+
+              If task(1:5) == b'ERROR' then there is an error in the
+              input arguments.
+        """
+        p5 = 0.5
+        p66 = 0.66
+        xtrapl = 1.1
+        xtrapu = 4.0
+
+        if task[:5] == b"START":
+            if stp < self.stpmin:
+                task = b"ERROR: STP .LT. STPMIN"
+            if stp > self.stpmax:
+                task = b"ERROR: STP .GT. STPMAX"
+            if g >= 0:
+                task = b"ERROR: INITIAL G .GE. ZERO"
+            if self.ftol < 0:
+                task = b"ERROR: FTOL .LT. ZERO"
+            if self.gtol < 0:
+                task = b"ERROR: GTOL .LT. ZERO"
+            if self.xtol < 0:
+                task = b"ERROR: XTOL .LT. ZERO"
+            if self.stpmin < 0:
+                task = b"ERROR: STPMIN .LT. ZERO"
+            if self.stpmax < self.stpmin:
+                task = b"ERROR: STPMAX .LT. STPMIN"
+
+            if task[:5] == b"ERROR":
+                return stp, f, g, task
+
+            # Initialize local variables.
+
+            self.brackt = False
+            self.stage = 1
+            self.finit = f
+            self.ginit = g
+            self.gtest = self.ftol * self.ginit
+            self.width = self.stpmax - self.stpmin
+            self.width1 = self.width / p5
+
+            # The variables stx, fx, gx contain the values of the step,
+            # function, and derivative at the best step.
+            # The variables sty, fy, gy contain the value of the step,
+            # function, and derivative at sty.
+            # The variables stp, f, g contain the values of the step,
+            # function, and derivative at stp.
+
+            self.stx = 0.0
+            self.fx = self.finit
+            self.gx = self.ginit
+            self.sty = 0.0
+            self.fy = self.finit
+            self.gy = self.ginit
+            self.stmin = 0
+            self.stmax = stp + xtrapu * stp
+            task = b"FG"
+            return stp, f, g, task
+
+        # in the original Fortran this was a location to restore variables
+        # we don't need to do that because they're attributes.
+
+        # If psi(stp) <= 0 and f'(stp) >= 0 for some step, then the
+        # algorithm enters the second stage.
+        ftest = self.finit + stp * self.gtest
+
+        if self.stage == 1 and f <= ftest and g >= 0:
+            self.stage = 2
+
+        # test for warnings
+        if self.brackt and (stp <= self.stmin or stp >= self.stmax):
+            task = b"WARNING: ROUNDING ERRORS PREVENT PROGRESS"
+        if self.brackt and self.stmax - self.stmin <= self.xtol * self.stmax:
+            task = b"WARNING: XTOL TEST SATISFIED"
+        if stp == self.stpmax and f <= ftest and g <= self.gtest:
+            task = b"WARNING: STP = STPMAX"
+        if stp == self.stpmin and (f > ftest or g >= self.gtest):
+            task = b"WARNING: STP = STPMIN"
+
+        # test for convergence
+        if f <= ftest and abs(g) <= self.gtol * -self.ginit:
+            task = b"CONVERGENCE"
+
+        # test for termination
+        if task[:4] == b"WARN" or task[:4] == b"CONV":
+            return stp, f, g, task
+
+        # A modified function is used to predict the step during the
+        # first stage if a lower function value has been obtained but
+        # the decrease is not sufficient.
+        if self.stage == 1 and f <= self.fx and f > ftest:
+            # Define the modified function and derivative values.
+            fm = f - stp * self.gtest
+            fxm = self.fx - self.stx * self.gtest
+            fym = self.fy - self.sty * self.gtest
+            gm = g - self.gtest
+            gxm = self.gx - self.gtest
+            gym = self.gy - self.gtest
+
+            # Call dcstep to update stx, sty, and to compute the new step.
+            # dcstep can have several operations which can produce NaN
+            # e.g. inf/inf. Filter these out.
+            with np.errstate(invalid="ignore", over="ignore"):
+                tup = dcstep(
+                    self.stx,
+                    fxm,
+                    gxm,
+                    self.sty,
+                    fym,
+                    gym,
+                    stp,
+                    fm,
+                    gm,
+                    self.brackt,
+                    self.stmin,
+                    self.stmax,
+                )
+                self.stx, fxm, gxm, self.sty, fym, gym, stp, self.brackt = tup
+
+            # Reset the function and derivative values for f
+            self.fx = fxm + self.stx * self.gtest
+            self.fy = fym + self.sty * self.gtest
+            self.gx = gxm + self.gtest
+            self.gy = gym + self.gtest
+
+        else:
+            # Call dcstep to update stx, sty, and to compute the new step.
+            # dcstep can have several operations which can produce NaN
+            # e.g. inf/inf. Filter these out.
+
+            with np.errstate(invalid="ignore", over="ignore"):
+                tup = dcstep(
+                    self.stx,
+                    self.fx,
+                    self.gx,
+                    self.sty,
+                    self.fy,
+                    self.gy,
+                    stp,
+                    f,
+                    g,
+                    self.brackt,
+                    self.stmin,
+                    self.stmax,
+                )
+            (
+                self.stx,
+                self.fx,
+                self.gx,
+                self.sty,
+                self.fy,
+                self.gy,
+                stp,
+                self.brackt,
+            ) = tup
+
+        # Decide if a bisection step is needed
+        if self.brackt:
+            if abs(self.sty - self.stx) >= p66 * self.width1:
+                stp = self.stx + p5 * (self.sty - self.stx)
+            self.width1 = self.width
+            self.width = abs(self.sty - self.stx)
+
+        # Set the minimum and maximum steps allowed for stp.
+        if self.brackt:
+            self.stmin = min(self.stx, self.sty)
+            self.stmax = max(self.stx, self.sty)
+        else:
+            self.stmin = stp + xtrapl * (stp - self.stx)
+            self.stmax = stp + xtrapu * (stp - self.stx)
+
+        # Force the step to be within the bounds stpmax and stpmin.
+        stp = np.clip(stp, self.stpmin, self.stpmax)
+
+        # If further progress is not possible, let stp be the best
+        # point obtained during the search.
+        if (
+            self.brackt
+            and (stp <= self.stmin or stp >= self.stmax)
+            or (
+                self.brackt
+                and self.stmax - self.stmin <= self.xtol * self.stmax
+            )
+        ):
+            stp = self.stx
+
+        # Obtain another function and derivative
+        task = b"FG"
+        return stp, f, g, task
+
+
+def dcstep(stx, fx, dx, sty, fy, dy, stp, fp, dp, brackt, stpmin, stpmax):
+    """
+    Subroutine dcstep
+
+    This subroutine computes a safeguarded step for a search
+    procedure and updates an interval that contains a step that
+    satisfies a sufficient decrease and a curvature condition.
+
+    The parameter stx contains the step with the least function
+    value. If brackt is set to .true. then a minimizer has
+    been bracketed in an interval with endpoints stx and sty.
+    The parameter stp contains the current step.
+    The subroutine assumes that if brackt is set to .true. then
+
+        min(stx,sty) < stp < max(stx,sty),
+
+    and that the derivative at stx is negative in the direction
+    of the step.
+
+    The subroutine statement is
+
+      subroutine dcstep(stx,fx,dx,sty,fy,dy,stp,fp,dp,brackt,
+                        stpmin,stpmax)
+
+    where
+
+    stx is a double precision variable.
+        On entry stx is the best step obtained so far and is an
+          endpoint of the interval that contains the minimizer.
+        On exit stx is the updated best step.
+
+    fx is a double precision variable.
+        On entry fx is the function at stx.
+        On exit fx is the function at stx.
+
+    dx is a double precision variable.
+        On entry dx is the derivative of the function at
+          stx. The derivative must be negative in the direction of
+          the step, that is, dx and stp - stx must have opposite
+          signs.
+        On exit dx is the derivative of the function at stx.
+
+    sty is a double precision variable.
+        On entry sty is the second endpoint of the interval that
+          contains the minimizer.
+        On exit sty is the updated endpoint of the interval that
+          contains the minimizer.
+
+    fy is a double precision variable.
+        On entry fy is the function at sty.
+        On exit fy is the function at sty.
+
+    dy is a double precision variable.
+        On entry dy is the derivative of the function at sty.
+        On exit dy is the derivative of the function at the exit sty.
+
+    stp is a double precision variable.
+        On entry stp is the current step. If brackt is set to .true.
+          then on input stp must be between stx and sty.
+        On exit stp is a new trial step.
+
+    fp is a double precision variable.
+        On entry fp is the function at stp
+        On exit fp is unchanged.
+
+    dp is a double precision variable.
+        On entry dp is the derivative of the function at stp.
+        On exit dp is unchanged.
+
+    brackt is an logical variable.
+        On entry brackt specifies if a minimizer has been bracketed.
+            Initially brackt must be set to .false.
+        On exit brackt specifies if a minimizer has been bracketed.
+            When a minimizer is bracketed brackt is set to .true.
+
+    stpmin is a double precision variable.
+        On entry stpmin is a lower bound for the step.
+        On exit stpmin is unchanged.
+
+    stpmax is a double precision variable.
+        On entry stpmax is an upper bound for the step.
+        On exit stpmax is unchanged.
+
+    MINPACK-1 Project. June 1983
+    Argonne National Laboratory.
+    Jorge J. More' and David J. Thuente.
+
+    MINPACK-2 Project. November 1993.
+    Argonne National Laboratory and University of Minnesota.
+    Brett M. Averick and Jorge J. More'.
+
+    """
+    sgn_dp = np.sign(dp)
+    sgn_dx = np.sign(dx)
+
+    # sgnd = dp * (dx / abs(dx))
+    sgnd = sgn_dp * sgn_dx
+
+    # First case: A higher function value. The minimum is bracketed.
+    # If the cubic step is closer to stx than the quadratic step, the
+    # cubic step is taken, otherwise the average of the cubic and
+    # quadratic steps is taken.
+    if fp > fx:
+        theta = 3.0 * (fx - fp) / (stp - stx) + dx + dp
+        s = max(abs(theta), abs(dx), abs(dp))
+        gamma = s * np.sqrt((theta / s) ** 2 - (dx / s) * (dp / s))
+        if stp < stx:
+            gamma *= -1
+        p = (gamma - dx) + theta
+        q = ((gamma - dx) + gamma) + dp
+        r = p / q
+        stpc = stx + r * (stp - stx)
+        stpq = stx + ((dx / ((fx - fp) / (stp - stx) + dx)) / 2.0) * (stp - stx)
+        if abs(stpc - stx) <= abs(stpq - stx):
+            stpf = stpc
+        else:
+            stpf = stpc + (stpq - stpc) / 2.0
+        brackt = True
+    elif sgnd < 0.0:
+        # Second case: A lower function value and derivatives of opposite
+        # sign. The minimum is bracketed. If the cubic step is farther from
+        # stp than the secant step, the cubic step is taken, otherwise the
+        # secant step is taken.
+        theta = 3 * (fx - fp) / (stp - stx) + dx + dp
+        s = max(abs(theta), abs(dx), abs(dp))
+        gamma = s * np.sqrt((theta / s) ** 2 - (dx / s) * (dp / s))
+        if stp > stx:
+            gamma *= -1
+        p = (gamma - dp) + theta
+        q = ((gamma - dp) + gamma) + dx
+        r = p / q
+        stpc = stp + r * (stx - stp)
+        stpq = stp + (dp / (dp - dx)) * (stx - stp)
+        if abs(stpc - stp) > abs(stpq - stp):
+            stpf = stpc
+        else:
+            stpf = stpq
+        brackt = True
+    elif abs(dp) < abs(dx):
+        # Third case: A lower function value, derivatives of the same sign,
+        # and the magnitude of the derivative decreases.
+
+        # The cubic step is computed only if the cubic tends to infinity
+        # in the direction of the step or if the minimum of the cubic
+        # is beyond stp. Otherwise the cubic step is defined to be the
+        # secant step.
+        theta = 3 * (fx - fp) / (stp - stx) + dx + dp
+        s = max(abs(theta), abs(dx), abs(dp))
+
+        # The case gamma = 0 only arises if the cubic does not tend
+        # to infinity in the direction of the step.
+        gamma = s * np.sqrt(max(0, (theta / s) ** 2 - (dx / s) * (dp / s)))
+        if stp > stx:
+            gamma = -gamma
+        p = (gamma - dp) + theta
+        q = (gamma + (dx - dp)) + gamma
+        r = p / q
+        if r < 0 and gamma != 0:
+            stpc = stp + r * (stx - stp)
+        elif stp > stx:
+            stpc = stpmax
+        else:
+            stpc = stpmin
+        stpq = stp + (dp / (dp - dx)) * (stx - stp)
+
+        if brackt:
+            # A minimizer has been bracketed. If the cubic step is
+            # closer to stp than the secant step, the cubic step is
+            # taken, otherwise the secant step is taken.
+            if abs(stpc - stp) < abs(stpq - stp):
+                stpf = stpc
+            else:
+                stpf = stpq
+
+            if stp > stx:
+                stpf = min(stp + 0.66 * (sty - stp), stpf)
+            else:
+                stpf = max(stp + 0.66 * (sty - stp), stpf)
+        else:
+            # A minimizer has not been bracketed. If the cubic step is
+            # farther from stp than the secant step, the cubic step is
+            # taken, otherwise the secant step is taken.
+            if abs(stpc - stp) > abs(stpq - stp):
+                stpf = stpc
+            else:
+                stpf = stpq
+            stpf = np.clip(stpf, stpmin, stpmax)
+
+    else:
+        # Fourth case: A lower function value, derivatives of the same sign,
+        # and the magnitude of the derivative does not decrease. If the
+        # minimum is not bracketed, the step is either stpmin or stpmax,
+        # otherwise the cubic step is taken.
+        if brackt:
+            theta = 3.0 * (fp - fy) / (sty - stp) + dy + dp
+            s = max(abs(theta), abs(dy), abs(dp))
+            gamma = s * np.sqrt((theta / s) ** 2 - (dy / s) * (dp / s))
+            if stp > sty:
+                gamma = -gamma
+            p = (gamma - dp) + theta
+            q = ((gamma - dp) + gamma) + dy
+            r = p / q
+            stpc = stp + r * (sty - stp)
+            stpf = stpc
+        elif stp > stx:
+            stpf = stpmax
+        else:
+            stpf = stpmin
+
+    # Update the interval which contains a minimizer.
+    if fp > fx:
+        sty = stp
+        fy = fp
+        dy = dp
+    else:
+        if sgnd < 0:
+            sty = stx
+            fy = fx
+            dy = dx
+        stx = stp
+        fx = fp
+        dx = dp
+
+    # Compute the new step.
+    stp = stpf
+
+    return stx, fx, dx, sty, fy, dy, stp, brackt

venv/lib/python3.13/site-packages/scipy/optimize/_differentiable_functions.py

@@ -0,0 +1,835 @@
+from collections import namedtuple
+
+import numpy as np
+import scipy.sparse as sps
+from ._numdiff import approx_derivative, group_columns
+from ._hessian_update_strategy import HessianUpdateStrategy
+from scipy.sparse.linalg import LinearOperator
+from scipy._lib._array_api import array_namespace, xp_copy
+from scipy._lib import array_api_extra as xpx
+from scipy._lib._util import _ScalarFunctionWrapper
+
+
+FD_METHODS = ('2-point', '3-point', 'cs')
+
+
+class _ScalarGradWrapper:
+    """
+    Wrapper class for gradient calculation
+    """
+    def __init__(
+            self,
+            grad,
+            fun=None,
+            args=None,
+            finite_diff_options=None,
+    ):
+        self.fun = fun
+        self.grad = grad
+        self.args = [] if args is None else args
+        self.finite_diff_options = finite_diff_options
+        self.ngev = 0
+        # number of function evaluations consumed by finite difference
+        self.nfev = 0
+
+    def __call__(self, x, f0=None, **kwds):
+        # Send a copy because the user may overwrite it.
+        # The user of this class might want `x` to remain unchanged.
+        if callable(self.grad):
+            g = np.atleast_1d(self.grad(np.copy(x), *self.args))
+        elif self.grad in FD_METHODS:
+            g, dct = approx_derivative(
+                self.fun,
+                x,
+                f0=f0,
+                **self.finite_diff_options,
+            )
+            self.nfev += dct['nfev']
+
+        self.ngev += 1
+        return g
+
+
+class _ScalarHessWrapper:
+    """
+    Wrapper class for hess calculation via finite differences
+    """
+    def __init__(
+            self,
+            hess,
+            x0=None,
+            grad=None,
+            args=None,
+            finite_diff_options=None,
+    ):
+        self.hess = hess
+        self.grad = grad
+        self.args = [] if args is None else args
+        self.finite_diff_options = finite_diff_options
+        # keep track of any finite difference function evaluations for grad
+        self.ngev = 0
+        self.nhev = 0
+        self.H = None
+        self._hess_func = None
+
+        if callable(hess):
+            self.H = hess(np.copy(x0), *args)
+            self.nhev += 1
+
+            if sps.issparse(self.H):
+                self._hess_func = self._sparse_callable
+                self.H = sps.csr_array(self.H)
+            elif isinstance(self.H, LinearOperator):
+                self._hess_func = self._linearoperator_callable
+            else:
+                # dense
+                self._hess_func = self._dense_callable
+                self.H = np.atleast_2d(np.asarray(self.H))
+        elif hess in FD_METHODS:
+                self._hess_func = self._fd_hess
+
+    def __call__(self, x, f0=None, **kwds):
+        return self._hess_func(np.copy(x), f0=f0)
+
+    def _fd_hess(self, x, f0=None, **kwds):
+        self.H, dct = approx_derivative(
+            self.grad, x, f0=f0, **self.finite_diff_options
+        )
+        self.ngev += dct["nfev"]
+        return self.H
+
+    def _sparse_callable(self, x, **kwds):
+        self.nhev += 1
+        self.H = sps.csr_array(self.hess(x, *self.args))
+        return self.H
+
+    def _dense_callable(self, x, **kwds):
+        self.nhev += 1
+        self.H = np.atleast_2d(
+            np.asarray(self.hess(x, *self.args))
+        )
+        return self.H
+
+    def _linearoperator_callable(self, x, **kwds):
+        self.nhev += 1
+        self.H = self.hess(x, *self.args)
+        return self.H
+
+
+class ScalarFunction:
+    """Scalar function and its derivatives.
+
+    This class defines a scalar function F: R^n->R and methods for
+    computing or approximating its first and second derivatives.
+
+    Parameters
+    ----------
+    fun : callable
+        evaluates the scalar function. Must be of the form ``fun(x, *args)``,
+        where ``x`` is the argument in the form of a 1-D array and ``args`` is
+        a tuple of any additional fixed parameters needed to completely specify
+        the function. Should return a scalar.
+    x0 : array-like
+        Provides an initial set of variables for evaluating fun. Array of real
+        elements of size (n,), where 'n' is the number of independent
+        variables.
+    args : tuple, optional
+        Any additional fixed parameters needed to completely specify the scalar
+        function.
+    grad : {callable, '2-point', '3-point', 'cs'}
+        Method for computing the gradient vector.
+        If it is a callable, it should be a function that returns the gradient
+        vector:
+
+            ``grad(x, *args) -> array_like, shape (n,)``
+
+        where ``x`` is an array with shape (n,) and ``args`` is a tuple with
+        the fixed parameters.
+        Alternatively, the keywords  {'2-point', '3-point', 'cs'} can be used
+        to select a finite difference scheme for numerical estimation of the
+        gradient with a relative step size. These finite difference schemes
+        obey any specified `bounds`.
+    hess : {callable, '2-point', '3-point', 'cs', HessianUpdateStrategy}
+        Method for computing the Hessian matrix. If it is callable, it should
+        return the  Hessian matrix:
+
+            ``hess(x, *args) -> {LinearOperator, spmatrix, array}, (n, n)``
+
+        where x is a (n,) ndarray and `args` is a tuple with the fixed
+        parameters. Alternatively, the keywords {'2-point', '3-point', 'cs'}
+        select a finite difference scheme for numerical estimation. Or, objects
+        implementing `HessianUpdateStrategy` interface can be used to
+        approximate the Hessian.
+        Whenever the gradient is estimated via finite-differences, the Hessian
+        cannot be estimated with options {'2-point', '3-point', 'cs'} and needs
+        to be estimated using one of the quasi-Newton strategies.
+    finite_diff_rel_step : None or array_like
+        Relative step size to use. The absolute step size is computed as
+        ``h = finite_diff_rel_step * sign(x0) * max(1, abs(x0))``, possibly
+        adjusted to fit into the bounds. For ``method='3-point'`` the sign
+        of `h` is ignored. If None then finite_diff_rel_step is selected
+        automatically,
+    finite_diff_bounds : tuple of array_like
+        Lower and upper bounds on independent variables. Defaults to no bounds,
+        (-np.inf, np.inf). Each bound must match the size of `x0` or be a
+        scalar, in the latter case the bound will be the same for all
+        variables. Use it to limit the range of function evaluation.
+    epsilon : None or array_like, optional
+        Absolute step size to use, possibly adjusted to fit into the bounds.
+        For ``method='3-point'`` the sign of `epsilon` is ignored. By default
+        relative steps are used, only if ``epsilon is not None`` are absolute
+        steps used.
+    workers : map-like callable, optional
+        A map-like callable, such as `multiprocessing.Pool.map` for evaluating
+        any numerical differentiation in parallel.
+        This evaluation is carried out as ``workers(fun, iterable)``, or
+        ``workers(grad, iterable)``, depending on what is being numerically
+        differentiated.
+        Alternatively, if `workers` is an int the task is subdivided into `workers`
+        sections and the function evaluated in parallel
+        (uses `multiprocessing.Pool <multiprocessing>`).
+        Supply -1 to use all available CPU cores.
+        It is recommended that a map-like be used instead of int, as repeated
+        calls to `approx_derivative` will incur large overhead from setting up
+        new processes.
+
+        .. versionadded:: 1.16.0
+
+    Notes
+    -----
+    This class implements a memoization logic. There are methods `fun`,
+    `grad`, hess` and corresponding attributes `f`, `g` and `H`. The following
+    things should be considered:
+
+        1. Use only public methods `fun`, `grad` and `hess`.
+        2. After one of the methods is called, the corresponding attribute
+           will be set. However, a subsequent call with a different argument
+           of *any* of the methods may overwrite the attribute.
+    """
+    def __init__(self, fun, x0, args, grad, hess, finite_diff_rel_step=None,
+                 finite_diff_bounds=(-np.inf, np.inf), epsilon=None, workers=None):
+
+        if not callable(grad) and grad not in FD_METHODS:
+            raise ValueError(
+                f"`grad` must be either callable or one of {FD_METHODS}."
+            )
+
+        if not (callable(hess) or hess in FD_METHODS
+                or isinstance(hess, HessianUpdateStrategy)):
+            raise ValueError(
+                f"`hess` must be either callable, HessianUpdateStrategy"
+                f" or one of {FD_METHODS}."
+            )
+
+        if grad in FD_METHODS and hess in FD_METHODS:
+            raise ValueError("Whenever the gradient is estimated via "
+                             "finite-differences, we require the Hessian "
+                             "to be estimated using one of the "
+                             "quasi-Newton strategies.")
+        self.xp = xp = array_namespace(x0)
+        _x = xpx.atleast_nd(xp.asarray(x0), ndim=1, xp=xp)
+        _dtype = xp.float64
+        if xp.isdtype(_x.dtype, "real floating"):
+            _dtype = _x.dtype
+
+        # original arguments
+        self._wrapped_fun = _ScalarFunctionWrapper(fun, args)
+        self._orig_fun = fun
+        self._orig_grad = grad
+        self._orig_hess = hess
+        self._args = args
+
+        # promotes to floating
+        self.x = xp.astype(_x, _dtype)
+        self.x_dtype = _dtype
+        self.n = self.x.size
+        self.f_updated = False
+        self.g_updated = False
+        self.H_updated = False
+
+        self._lowest_x = None
+        self._lowest_f = np.inf
+
+        # normalize workers
+        workers = workers or map
+
+        finite_diff_options = {}
+        if grad in FD_METHODS:
+            finite_diff_options["method"] = grad
+            finite_diff_options["rel_step"] = finite_diff_rel_step
+            finite_diff_options["abs_step"] = epsilon
+            finite_diff_options["bounds"] = finite_diff_bounds
+            finite_diff_options["workers"] = workers
+            finite_diff_options["full_output"] = True
+        if hess in FD_METHODS:
+            finite_diff_options["method"] = hess
+            finite_diff_options["rel_step"] = finite_diff_rel_step
+            finite_diff_options["abs_step"] = epsilon
+            finite_diff_options["as_linear_operator"] = True
+            finite_diff_options["workers"] = workers
+            finite_diff_options["full_output"] = True
+
+        # Initial function evaluation
+        self._nfev = 0
+        self._update_fun()
+
+        # Initial gradient evaluation
+        self._wrapped_grad = _ScalarGradWrapper(
+            grad,
+            fun=self._wrapped_fun,
+            args=args,
+            finite_diff_options=finite_diff_options,
+        )
+        self._update_grad()
+
+        # Hessian evaluation
+        if isinstance(hess, HessianUpdateStrategy):
+            self.H = hess
+            self.H.initialize(self.n, 'hess')
+            self.H_updated = True
+            self.x_prev = None
+            self.g_prev = None
+            _FakeCounter = namedtuple('_FakeCounter', ['ngev', 'nhev'])
+            self._wrapped_hess = _FakeCounter(ngev=0, nhev=0)
+        else:
+            if callable(hess):
+                self._wrapped_hess = _ScalarHessWrapper(
+                    hess,
+                    x0=x0,
+                    args=args,
+                    finite_diff_options=finite_diff_options
+                )
+                self.H = self._wrapped_hess.H
+                self.H_updated = True
+            elif hess in FD_METHODS:
+                self._wrapped_hess = _ScalarHessWrapper(
+                    hess,
+                    x0=x0,
+                    args=args,
+                    grad=self._wrapped_grad,
+                    finite_diff_options=finite_diff_options
+                )
+                self._update_grad()
+                self.H = self._wrapped_hess(self.x, f0=self.g)
+                self.H_updated = True
+
+    @property
+    def nfev(self):
+        return self._nfev + self._wrapped_grad.nfev
+
+    @property
+    def ngev(self):
+        return self._wrapped_grad.ngev  #+ self._wrapped_hess.ngev
+
+    @property
+    def nhev(self):
+        return self._wrapped_hess.nhev
+
+    def _update_x(self, x):
+        if isinstance(self._orig_hess, HessianUpdateStrategy):
+            self._update_grad()
+            self.x_prev = self.x
+            self.g_prev = self.g
+            # ensure that self.x is a copy of x. Don't store a reference
+            # otherwise the memoization doesn't work properly.
+
+            _x = xpx.atleast_nd(self.xp.asarray(x), ndim=1, xp=self.xp)
+            self.x = self.xp.astype(_x, self.x_dtype)
+            self.f_updated = False
+            self.g_updated = False
+            self.H_updated = False
+            self._update_hess()
+        else:
+            # ensure that self.x is a copy of x. Don't store a reference
+            # otherwise the memoization doesn't work properly.
+            _x = xpx.atleast_nd(self.xp.asarray(x), ndim=1, xp=self.xp)
+            self.x = self.xp.astype(_x, self.x_dtype)
+            self.f_updated = False
+            self.g_updated = False
+            self.H_updated = False
+
+    def _update_fun(self):
+        if not self.f_updated:
+            fx = self._wrapped_fun(self.x)
+            self._nfev += 1
+            if fx < self._lowest_f:
+                self._lowest_x = self.x
+                self._lowest_f = fx
+
+            self.f = fx
+            self.f_updated = True
+
+    def _update_grad(self):
+        if not self.g_updated:
+            if self._orig_grad in FD_METHODS:
+                self._update_fun()
+            self.g = self._wrapped_grad(self.x, f0=self.f)
+            self.g_updated = True
+
+    def _update_hess(self):
+        if not self.H_updated:
+            if self._orig_hess in FD_METHODS:
+                self._update_grad()
+                self.H = self._wrapped_hess(self.x, f0=self.g)
+            elif isinstance(self._orig_hess, HessianUpdateStrategy):
+                self._update_grad()
+                self.H.update(self.x - self.x_prev, self.g - self.g_prev)
+            else:       # should be callable(hess)
+                self.H = self._wrapped_hess(self.x)
+
+            self.H_updated = True
+
+    def fun(self, x):
+        if not np.array_equal(x, self.x):
+            self._update_x(x)
+        self._update_fun()
+        return self.f
+
+    def grad(self, x):
+        if not np.array_equal(x, self.x):
+            self._update_x(x)
+        self._update_grad()
+        return self.g
+
+    def hess(self, x):
+        if not np.array_equal(x, self.x):
+            self._update_x(x)
+        self._update_hess()
+        return self.H
+
+    def fun_and_grad(self, x):
+        if not np.array_equal(x, self.x):
+            self._update_x(x)
+        self._update_fun()
+        self._update_grad()
+        return self.f, self.g
+
+
+class _VectorFunWrapper:
+    def __init__(self, fun):
+        self.fun = fun
+        self.nfev = 0
+
+    def __call__(self, x):
+        self.nfev += 1
+        return np.atleast_1d(self.fun(x))
+
+
+class _VectorJacWrapper:
+    """
+    Wrapper class for Jacobian calculation
+    """
+    def __init__(
+            self,
+            jac,
+            fun=None,
+            finite_diff_options=None,
+            sparse_jacobian=None
+    ):
+        self.fun = fun
+        self.jac = jac
+        self.finite_diff_options = finite_diff_options
+        self.sparse_jacobian = sparse_jacobian
+
+        self.njev = 0
+        # number of function evaluations consumed by finite difference
+        self.nfev = 0
+
+    def __call__(self, x, f0=None, **kwds):
+        # Send a copy because the user may overwrite it.
+        # The user of this class might want `x` to remain unchanged.
+        if callable(self.jac):
+            J = self.jac(x)
+            self.njev += 1
+        elif self.jac in FD_METHODS:
+            J, dct = approx_derivative(
+                self.fun,
+                x,
+                f0=f0,
+                **self.finite_diff_options,
+            )
+            self.nfev += dct['nfev']
+
+        if self.sparse_jacobian:
+            return sps.csr_array(J)
+        elif sps.issparse(J):
+            return J.toarray()
+        elif isinstance(J, LinearOperator):
+            return J
+        else:
+            return np.atleast_2d(J)
+
+
+class _VectorHessWrapper:
+    """
+    Wrapper class for Jacobian calculation
+    """
+    def __init__(
+            self,
+            hess,
+            jac=None,
+            finite_diff_options=None,
+    ):
+        self.jac = jac
+        self.hess = hess
+        self.finite_diff_options = finite_diff_options
+        self.nhev = 0
+        # number of jac evaluations consumed by finite difference
+        self.njev = 0
+
+    def __call__(self, x, v, J0=None, **kwds):
+        # Send a copy because the user may overwrite it.
+        # The user of this class might want `x` to remain unchanged.
+        if callable(self.hess):
+            self.nhev += 1
+            return self._callable_hess(x, v)
+        elif self.hess in FD_METHODS:
+            return self._fd_hess(x, v, J0=J0)
+
+    def _fd_hess(self, x, v, J0=None):
+        if J0 is None:
+            J0 = self.jac(x)
+            self.njev += 1
+
+        # H will be a LinearOperator
+        H = approx_derivative(self.jac_dot_v, x,
+                              f0=J0.T.dot(v),
+                              args=(v,),
+                              **self.finite_diff_options)
+        return H
+
+    def jac_dot_v(self, x, v):
+        self.njev += 1
+        return self.jac(x).T.dot(v)
+
+    def _callable_hess(self, x, v):
+        H = self.hess(x, v)
+
+        if sps.issparse(H):
+            return sps.csr_array(H)
+        elif isinstance(H, LinearOperator):
+            return H
+        else:
+            return np.atleast_2d(np.asarray(H))
+
+
+class VectorFunction:
+    """Vector function and its derivatives.
+
+    This class defines a vector function F: R^n->R^m and methods for
+    computing or approximating its first and second derivatives.
+
+    Notes
+    -----
+    This class implements a memoization logic. There are methods `fun`,
+    `jac`, hess` and corresponding attributes `f`, `J` and `H`. The following
+    things should be considered:
+
+        1. Use only public methods `fun`, `jac` and `hess`.
+        2. After one of the methods is called, the corresponding attribute
+           will be set. However, a subsequent call with a different argument
+           of *any* of the methods may overwrite the attribute.
+    """
+    def __init__(self, fun, x0, jac, hess,
+                 finite_diff_rel_step=None, finite_diff_jac_sparsity=None,
+                 finite_diff_bounds=(-np.inf, np.inf), sparse_jacobian=None,
+                 workers=None):
+        if not callable(jac) and jac not in FD_METHODS:
+            raise ValueError(f"`jac` must be either callable or one of {FD_METHODS}.")
+
+        if not (callable(hess) or hess in FD_METHODS
+                or isinstance(hess, HessianUpdateStrategy)):
+            raise ValueError("`hess` must be either callable,"
+                             f"HessianUpdateStrategy or one of {FD_METHODS}.")
+
+        if jac in FD_METHODS and hess in FD_METHODS:
+            raise ValueError("Whenever the Jacobian is estimated via "
+                             "finite-differences, we require the Hessian to "
+                             "be estimated using one of the quasi-Newton "
+                             "strategies.")
+
+        self.xp = xp = array_namespace(x0)
+        _x = xpx.atleast_nd(xp.asarray(x0), ndim=1, xp=xp)
+        _dtype = xp.float64
+        if xp.isdtype(_x.dtype, "real floating"):
+            _dtype = _x.dtype
+
+        # store original functions
+        self._orig_fun = fun
+        self._orig_jac = jac
+        self._orig_hess = hess
+
+        # promotes to floating, ensures that it's a copy
+        self.x = xp.astype(_x, _dtype)
+        self.x_dtype = _dtype
+
+        self.n = self.x.size
+        self._nfev = 0
+        self._njev = 0
+        self._nhev = 0
+        self.f_updated = False
+        self.J_updated = False
+        self.H_updated = False
+
+        # normalize workers
+        workers = workers or map
+
+        finite_diff_options = {}
+        if jac in FD_METHODS:
+            finite_diff_options["method"] = jac
+            finite_diff_options["rel_step"] = finite_diff_rel_step
+            if finite_diff_jac_sparsity is not None:
+                sparsity_groups = group_columns(finite_diff_jac_sparsity)
+                finite_diff_options["sparsity"] = (finite_diff_jac_sparsity,
+                                                   sparsity_groups)
+            finite_diff_options["bounds"] = finite_diff_bounds
+            finite_diff_options["workers"] = workers
+            finite_diff_options["full_output"] = True
+            self.x_diff = np.copy(self.x)
+        if hess in FD_METHODS:
+            finite_diff_options["method"] = hess
+            finite_diff_options["rel_step"] = finite_diff_rel_step
+            finite_diff_options["as_linear_operator"] = True
+            # workers is not useful for evaluation of the LinearOperator
+            # produced by approx_derivative. Only two/three function
+            # evaluations are used, and the LinearOperator may persist
+            # outside the scope that workers is valid in.
+            self.x_diff = np.copy(self.x)
+        if jac in FD_METHODS and hess in FD_METHODS:
+            raise ValueError("Whenever the Jacobian is estimated via "
+                             "finite-differences, we require the Hessian to "
+                             "be estimated using one of the quasi-Newton "
+                             "strategies.")
+
+        self.fun_wrapped = _VectorFunWrapper(fun)
+        self._update_fun()
+
+        self.v = np.zeros_like(self.f)
+        self.m = self.v.size
+
+        # Initial Jacobian Evaluation
+        if callable(jac):
+            self.J = jac(xp_copy(self.x))
+            self.J_updated = True
+            self._njev += 1
+        elif jac in FD_METHODS:
+            self.J, dct = approx_derivative(
+                self.fun_wrapped, self.x, f0=self.f, **finite_diff_options
+            )
+            self.J_updated = True
+            self._nfev += dct['nfev']
+
+        self.sparse_jacobian = False
+        if (sparse_jacobian or
+                sparse_jacobian is None and sps.issparse(self.J)):
+            # something truthy was specified for sparse_jacobian,
+            # or it turns out that the Jacobian was sparse.
+            self.J = sps.csr_array(self.J)
+            self.sparse_jacobian = True
+        elif sps.issparse(self.J):
+            self.J = self.J.toarray()
+        elif isinstance(self.J, LinearOperator):
+            pass
+        else:
+            self.J = np.atleast_2d(self.J)
+
+        self.jac_wrapped = _VectorJacWrapper(
+            jac,
+            fun=self.fun_wrapped,
+            finite_diff_options=finite_diff_options,
+            sparse_jacobian=self.sparse_jacobian
+        )
+
+        self.hess_wrapped = _VectorHessWrapper(
+            hess, jac=self.jac_wrapped, finite_diff_options=finite_diff_options
+        )
+
+        # Define Hessian
+        if callable(hess) or hess in FD_METHODS:
+            self.H = self.hess_wrapped(xp_copy(self.x), self.v, J0=self.J)
+            self.H_updated = True
+            if callable(hess):
+                self._nhev += 1
+        elif isinstance(hess, HessianUpdateStrategy):
+            self.H = hess
+            self.H.initialize(self.n, 'hess')
+            self.H_updated = True
+            self.x_prev = None
+            self.J_prev = None
+
+    @property
+    def nfev(self):
+        return self._nfev + self.jac_wrapped.nfev
+
+    @property
+    def njev(self):
+        return self._njev + self.hess_wrapped.njev
+
+    @property
+    def nhev(self):
+        return self._nhev
+
+    def _update_v(self, v):
+        if not np.array_equal(v, self.v):
+            self.v = v
+            self.H_updated = False
+
+    def _update_x(self, x):
+        if not np.array_equal(x, self.x):
+            if isinstance(self._orig_hess, HessianUpdateStrategy):
+                self._update_jac()
+                self.x_prev = self.x
+                self.J_prev = self.J
+                _x = xpx.atleast_nd(self.xp.asarray(x), ndim=1, xp=self.xp)
+                self.x = self.xp.astype(_x, self.x_dtype)
+                self.f_updated = False
+                self.J_updated = False
+                self.H_updated = False
+                self._update_hess()
+            else:
+                _x = xpx.atleast_nd(self.xp.asarray(x), ndim=1, xp=self.xp)
+                self.x = self.xp.astype(_x, self.x_dtype)
+                self.f_updated = False
+                self.J_updated = False
+                self.H_updated = False
+
+    def _update_fun(self):
+        if not self.f_updated:
+            self.f = self.fun_wrapped(xp_copy(self.x))
+            self._nfev += 1
+            self.f_updated = True
+
+    def _update_jac(self):
+        if not self.J_updated:
+            if self._orig_jac in FD_METHODS:
+                # need to update fun to get f0
+                self._update_fun()
+            else:
+                self._njev += 1
+
+            self.J = self.jac_wrapped(xp_copy(self.x), f0=self.f)
+            self.J_updated = True
+
+    def _update_hess(self):
+        if not self.H_updated:
+            if callable(self._orig_hess):
+                self.H = self.hess_wrapped(xp_copy(self.x), self.v)
+                self._nhev += 1
+            elif self._orig_hess in FD_METHODS:
+                self._update_jac()
+                self.H = self.hess_wrapped(xp_copy(self.x), self.v, J0=self.J)
+            elif isinstance(self._orig_hess, HessianUpdateStrategy):
+                self._update_jac()
+                # When v is updated before x was updated, then x_prev and
+                # J_prev are None and we need this check.
+                if self.x_prev is not None and self.J_prev is not None:
+                    delta_x = self.x - self.x_prev
+                    delta_g = self.J.T.dot(self.v) - self.J_prev.T.dot(self.v)
+                    self.H.update(delta_x, delta_g)
+
+            self.H_updated = True
+
+    def fun(self, x):
+        self._update_x(x)
+        self._update_fun()
+        # returns a copy so that downstream can't overwrite the
+        # internal attribute
+        return xp_copy(self.f)
+
+    def jac(self, x):
+        self._update_x(x)
+        self._update_jac()
+        if hasattr(self.J, "astype"):
+            # returns a copy so that downstream can't overwrite the
+            # internal attribute. But one can't copy a LinearOperator
+            return self.J.astype(self.J.dtype)
+        return self.J
+
+    def hess(self, x, v):
+        # v should be updated before x.
+        self._update_v(v)
+        self._update_x(x)
+        self._update_hess()
+        if hasattr(self.H, "astype"):
+            # returns a copy so that downstream can't overwrite the
+            # internal attribute. But one can't copy non-arrays
+            return self.H.astype(self.H.dtype)
+        return self.H
+
+
+class LinearVectorFunction:
+    """Linear vector function and its derivatives.
+
+    Defines a linear function F = A x, where x is N-D vector and
+    A is m-by-n matrix. The Jacobian is constant and equals to A. The Hessian
+    is identically zero and it is returned as a csr matrix.
+    """
+    def __init__(self, A, x0, sparse_jacobian):
+        if sparse_jacobian or sparse_jacobian is None and sps.issparse(A):
+            self.J = sps.csr_array(A)
+            self.sparse_jacobian = True
+        elif sps.issparse(A):
+            self.J = A.toarray()
+            self.sparse_jacobian = False
+        else:
+            # np.asarray makes sure A is ndarray and not matrix
+            self.J = np.atleast_2d(np.asarray(A))
+            self.sparse_jacobian = False
+
+        self.m, self.n = self.J.shape
+
+        self.xp = xp = array_namespace(x0)
+        _x = xpx.atleast_nd(xp.asarray(x0), ndim=1, xp=xp)
+        _dtype = xp.float64
+        if xp.isdtype(_x.dtype, "real floating"):
+            _dtype = _x.dtype
+
+        # promotes to floating
+        self.x = xp.astype(_x, _dtype)
+        self.x_dtype = _dtype
+
+        self.f = self.J.dot(self.x)
+        self.f_updated = True
+
+        self.v = np.zeros(self.m, dtype=float)
+        self.H = sps.csr_array((self.n, self.n))
+
+    def _update_x(self, x):
+        if not np.array_equal(x, self.x):
+            _x = xpx.atleast_nd(self.xp.asarray(x), ndim=1, xp=self.xp)
+            self.x = self.xp.astype(_x, self.x_dtype)
+            self.f_updated = False
+
+    def fun(self, x):
+        self._update_x(x)
+        if not self.f_updated:
+            self.f = self.J.dot(x)
+            self.f_updated = True
+        return self.f
+
+    def jac(self, x):
+        self._update_x(x)
+        return self.J
+
+    def hess(self, x, v):
+        self._update_x(x)
+        self.v = v
+        return self.H
+
+
+class IdentityVectorFunction(LinearVectorFunction):
+    """Identity vector function and its derivatives.
+
+    The Jacobian is the identity matrix, returned as a dense array when
+    `sparse_jacobian=False` and as a csr matrix otherwise. The Hessian is
+    identically zero and it is returned as a csr matrix.
+    """
+    def __init__(self, x0, sparse_jacobian):
+        n = len(x0)
+        if sparse_jacobian or sparse_jacobian is None:
+            A = sps.eye_array(n, format='csr')
+            sparse_jacobian = True
+        else:
+            A = np.eye(n)
+            sparse_jacobian = False
+        super().__init__(A, x0, sparse_jacobian)

venv/lib/python3.13/site-packages/scipy/optimize/_direct_py.py

@@ -0,0 +1,280 @@
+from typing import (  # noqa: UP035
+    Any, Callable, Iterable
+)
+
+import numpy as np
+from scipy.optimize import OptimizeResult
+from ._constraints import old_bound_to_new, Bounds
+from ._direct import direct as _direct  # type: ignore
+
+__all__ = ['direct']
+
+ERROR_MESSAGES = (
+    "Number of function evaluations done is larger than maxfun={}",
+    "Number of iterations is larger than maxiter={}",
+    "u[i] < l[i] for some i",
+    "maxfun is too large",
+    "Initialization failed",
+    "There was an error in the creation of the sample points",
+    "An error occurred while the function was sampled",
+    "Maximum number of levels has been reached.",
+    "Forced stop",
+    "Invalid arguments",
+    "Out of memory",
+)
+
+SUCCESS_MESSAGES = (
+    ("The best function value found is within a relative error={} "
+     "of the (known) global optimum f_min"),
+    ("The volume of the hyperrectangle containing the lowest function value "
+     "found is below vol_tol={}"),
+    ("The side length measure of the hyperrectangle containing the lowest "
+     "function value found is below len_tol={}"),
+)
+
+
+def direct(
+    func: Callable[
+        [np.ndarray[tuple[int], np.dtype[np.float64]]],
+        float | np.floating[Any] | np.integer[Any] | np.bool_,
+    ],
+    bounds: Iterable | Bounds,
+    *,
+    args: tuple = (),
+    eps: float = 1e-4,
+    maxfun: int | None = None,
+    maxiter: int = 1000,
+    locally_biased: bool = True,
+    f_min: float = -np.inf,
+    f_min_rtol: float = 1e-4,
+    vol_tol: float = 1e-16,
+    len_tol: float = 1e-6,
+    callback: Callable[
+        [np.ndarray[tuple[int], np.dtype[np.float64]]],
+        object,
+    ] | None = None,
+) -> OptimizeResult:
+    """
+    Finds the global minimum of a function using the
+    DIRECT algorithm.
+
+    Parameters
+    ----------
+    func : callable
+        The objective function to be minimized.
+        ``func(x, *args) -> float``
+        where ``x`` is an 1-D array with shape (n,) and ``args`` is a tuple of
+        the fixed parameters needed to completely specify the function.
+    bounds : sequence or `Bounds`
+        Bounds for variables. There are two ways to specify the bounds:
+
+        1. Instance of `Bounds` class.
+        2. ``(min, max)`` pairs for each element in ``x``.
+
+    args : tuple, optional
+        Any additional fixed parameters needed to
+        completely specify the objective function.
+    eps : float, optional
+        Minimal required difference of the objective function values
+        between the current best hyperrectangle and the next potentially
+        optimal hyperrectangle to be divided. In consequence, `eps` serves as a
+        tradeoff between local and global search: the smaller, the more local
+        the search becomes. Default is 1e-4.
+    maxfun : int or None, optional
+        Approximate upper bound on objective function evaluations.
+        If `None`, will be automatically set to ``1000 * N`` where ``N``
+        represents the number of dimensions. Will be capped if necessary to
+        limit DIRECT's RAM usage to app. 1GiB. This will only occur for very
+        high dimensional problems and excessive `max_fun`. Default is `None`.
+    maxiter : int, optional
+        Maximum number of iterations. Default is 1000.
+    locally_biased : bool, optional
+        If `True` (default), use the locally biased variant of the
+        algorithm known as DIRECT_L. If `False`, use the original unbiased
+        DIRECT algorithm. For hard problems with many local minima,
+        `False` is recommended.
+    f_min : float, optional
+        Function value of the global optimum. Set this value only if the
+        global optimum is known. Default is ``-np.inf``, so that this
+        termination criterion is deactivated.
+    f_min_rtol : float, optional
+        Terminate the optimization once the relative error between the
+        current best minimum `f` and the supplied global minimum `f_min`
+        is smaller than `f_min_rtol`. This parameter is only used if
+        `f_min` is also set. Must lie between 0 and 1. Default is 1e-4.
+    vol_tol : float, optional
+        Terminate the optimization once the volume of the hyperrectangle
+        containing the lowest function value is smaller than `vol_tol`
+        of the complete search space. Must lie between 0 and 1.
+        Default is 1e-16.
+    len_tol : float, optional
+        If ``locally_biased=True``, terminate the optimization once half of
+        the normalized maximal side length of the hyperrectangle containing
+        the lowest function value is smaller than `len_tol`.
+        If ``locally_biased=False``, terminate the optimization once half of
+        the normalized diagonal of the hyperrectangle containing the lowest
+        function value is smaller than `len_tol`. Must lie between 0 and 1.
+        Default is 1e-6.
+    callback : callable, optional
+        A callback function with signature ``callback(xk)`` where ``xk``
+        represents the best function value found so far.
+
+    Returns
+    -------
+    res : OptimizeResult
+        The optimization result represented as a ``OptimizeResult`` object.
+        Important attributes are: ``x`` the solution array, ``success`` a
+        Boolean flag indicating if the optimizer exited successfully and
+        ``message`` which describes the cause of the termination. See
+        `OptimizeResult` for a description of other attributes.
+
+    Notes
+    -----
+    DIviding RECTangles (DIRECT) is a deterministic global
+    optimization algorithm capable of minimizing a black box function with
+    its variables subject to lower and upper bound constraints by sampling
+    potential solutions in the search space [1]_. The algorithm starts by
+    normalising the search space to an n-dimensional unit hypercube.
+    It samples the function at the center of this hypercube and at 2n
+    (n is the number of variables) more points, 2 in each coordinate
+    direction. Using these function values, DIRECT then divides the
+    domain into hyperrectangles, each having exactly one of the sampling
+    points as its center. In each iteration, DIRECT chooses, using the `eps`
+    parameter which defaults to 1e-4, some of the existing hyperrectangles
+    to be further divided. This division process continues until either the
+    maximum number of iterations or maximum function evaluations allowed
+    are exceeded, or the hyperrectangle containing the minimal value found
+    so far becomes small enough. If `f_min` is specified, the optimization
+    will stop once this function value is reached within a relative tolerance.
+    The locally biased variant of DIRECT (originally called DIRECT_L) [2]_ is
+    used by default. It makes the search more locally biased and more
+    efficient for cases with only a few local minima.
+
+    A note about termination criteria: `vol_tol` refers to the volume of the
+    hyperrectangle containing the lowest function value found so far. This
+    volume decreases exponentially with increasing dimensionality of the
+    problem. Therefore `vol_tol` should be decreased to avoid premature
+    termination of the algorithm for higher dimensions. This does not hold
+    for `len_tol`: it refers either to half of the maximal side length
+    (for ``locally_biased=True``) or half of the diagonal of the
+    hyperrectangle (for ``locally_biased=False``).
+
+    This code is based on the DIRECT 2.0.4 Fortran code by Gablonsky et al. at
+    https://ctk.math.ncsu.edu/SOFTWARE/DIRECTv204.tar.gz .
+    This original version was initially converted via f2c and then cleaned up
+    and reorganized by Steven G. Johnson, August 2007, for the NLopt project.
+    The `direct` function wraps the C implementation.
+
+    .. versionadded:: 1.9.0
+
+    References
+    ----------
+    .. [1] Jones, D.R., Perttunen, C.D. & Stuckman, B.E. Lipschitzian
+        optimization without the Lipschitz constant. J Optim Theory Appl
+        79, 157-181 (1993).
+    .. [2] Gablonsky, J., Kelley, C. A Locally-Biased form of the DIRECT
+        Algorithm. Journal of Global Optimization 21, 27-37 (2001).
+
+    Examples
+    --------
+    The following example is a 2-D problem with four local minima: minimizing
+    the Styblinski-Tang function
+    (https://en.wikipedia.org/wiki/Test_functions_for_optimization).
+
+    >>> from scipy.optimize import direct, Bounds
+    >>> def styblinski_tang(pos):
+    ...     x, y = pos
+    ...     return 0.5 * (x**4 - 16*x**2 + 5*x + y**4 - 16*y**2 + 5*y)
+    >>> bounds = Bounds([-4., -4.], [4., 4.])
+    >>> result = direct(styblinski_tang, bounds)
+    >>> result.x, result.fun, result.nfev
+    array([-2.90321597, -2.90321597]), -78.3323279095383, 2011
+
+    The correct global minimum was found but with a huge number of function
+    evaluations (2011). Loosening the termination tolerances `vol_tol` and
+    `len_tol` can be used to stop DIRECT earlier.
+
+    >>> result = direct(styblinski_tang, bounds, len_tol=1e-3)
+    >>> result.x, result.fun, result.nfev
+    array([-2.9044353, -2.9044353]), -78.33230330754142, 207
+
+    """
+    # convert bounds to new Bounds class if necessary
+    if not isinstance(bounds, Bounds):
+        if isinstance(bounds, list) or isinstance(bounds, tuple):
+            lb, ub = old_bound_to_new(bounds)
+            bounds = Bounds(lb, ub)
+        else:
+            message = ("bounds must be a sequence or "
+                       "instance of Bounds class")
+            raise ValueError(message)
+
+    lb = np.ascontiguousarray(bounds.lb, dtype=np.float64)
+    ub = np.ascontiguousarray(bounds.ub, dtype=np.float64)
+
+    # validate bounds
+    # check that lower bounds are smaller than upper bounds
+    if not np.all(lb < ub):
+        raise ValueError('Bounds are not consistent min < max')
+    # check for infs
+    if (np.any(np.isinf(lb)) or np.any(np.isinf(ub))):
+        raise ValueError("Bounds must not be inf.")
+
+    # validate tolerances
+    if (vol_tol < 0 or vol_tol > 1):
+        raise ValueError("vol_tol must be between 0 and 1.")
+    if (len_tol < 0 or len_tol > 1):
+        raise ValueError("len_tol must be between 0 and 1.")
+    if (f_min_rtol < 0 or f_min_rtol > 1):
+        raise ValueError("f_min_rtol must be between 0 and 1.")
+
+    # validate maxfun and maxiter
+    if maxfun is None:
+        maxfun = 1000 * lb.shape[0]
+    if not isinstance(maxfun, int):
+        raise ValueError("maxfun must be of type int.")
+    if maxfun < 0:
+        raise ValueError("maxfun must be > 0.")
+    if not isinstance(maxiter, int):
+        raise ValueError("maxiter must be of type int.")
+    if maxiter < 0:
+        raise ValueError("maxiter must be > 0.")
+
+    # validate boolean parameters
+    if not isinstance(locally_biased, bool):
+        raise ValueError("locally_biased must be True or False.")
+
+    def _func_wrap(x, args=None):
+        x = np.asarray(x)
+        if args is None:
+            f = func(x)
+        else:
+            f = func(x, *args)
+        # always return a float
+        return np.asarray(f).item()
+
+    # TODO: fix disp argument
+    x, fun, ret_code, nfev, nit = _direct(
+        _func_wrap,
+        np.asarray(lb), np.asarray(ub),
+        args,
+        False, eps, maxfun, maxiter,
+        locally_biased,
+        f_min, f_min_rtol,
+        vol_tol, len_tol, callback
+    )
+
+    format_val = (maxfun, maxiter, f_min_rtol, vol_tol, len_tol)
+    if ret_code > 2:
+        message = SUCCESS_MESSAGES[ret_code - 3].format(
+                    format_val[ret_code - 1])
+    elif 0 < ret_code <= 2:
+        message = ERROR_MESSAGES[ret_code - 1].format(format_val[ret_code - 1])
+    elif 0 > ret_code > -100:
+        message = ERROR_MESSAGES[abs(ret_code) + 1]
+    else:
+        message = ERROR_MESSAGES[ret_code + 99]
+
+    return OptimizeResult(x=np.asarray(x), fun=fun, status=ret_code,
+                          success=ret_code > 2, message=message,
+                          nfev=nfev, nit=nit)

venv/lib/python3.13/site-packages/scipy/optimize/_dual_annealing.py

@@ -0,0 +1,732 @@
+# Dual Annealing implementation.
+# Copyright (c) 2018 Sylvain Gubian <sylvain.gubian@pmi.com>,
+# Yang Xiang <yang.xiang@pmi.com>
+# Author: Sylvain Gubian, Yang Xiang, PMP S.A.
+
+"""
+A Dual Annealing global optimization algorithm
+"""
+
+import numpy as np
+from scipy.optimize import OptimizeResult
+from scipy.optimize import minimize, Bounds
+from scipy.special import gammaln
+from scipy._lib._util import check_random_state, _transition_to_rng
+from scipy.optimize._constraints import new_bounds_to_old
+
+__all__ = ['dual_annealing']
+
+
+class VisitingDistribution:
+    """
+    Class used to generate new coordinates based on the distorted
+    Cauchy-Lorentz distribution. Depending on the steps within the strategy
+    chain, the class implements the strategy for generating new location
+    changes.
+
+    Parameters
+    ----------
+    lb : array_like
+        A 1-D NumPy ndarray containing lower bounds of the generated
+        components. Neither NaN or inf are allowed.
+    ub : array_like
+        A 1-D NumPy ndarray containing upper bounds for the generated
+        components. Neither NaN or inf are allowed.
+    visiting_param : float
+        Parameter for visiting distribution. Default value is 2.62.
+        Higher values give the visiting distribution a heavier tail, this
+        makes the algorithm jump to a more distant region.
+        The value range is (1, 3]. Its value is fixed for the life of the
+        object.
+    rng_gen : {`~numpy.random.Generator`}
+        A `~numpy.random.Generator` object for generating new locations.
+        (can be a `~numpy.random.RandomState` object until SPEC007 transition
+         is fully complete).
+
+    """
+    TAIL_LIMIT = 1.e8
+    MIN_VISIT_BOUND = 1.e-10
+
+    def __init__(self, lb, ub, visiting_param, rng_gen):
+        # if you wish to make _visiting_param adjustable during the life of
+        # the object then _factor2, _factor3, _factor5, _d1, _factor6 will
+        # have to be dynamically calculated in `visit_fn`. They're factored
+        # out here so they don't need to be recalculated all the time.
+        self._visiting_param = visiting_param
+        self.rng_gen = rng_gen
+        self.lower = lb
+        self.upper = ub
+        self.bound_range = ub - lb
+
+        # these are invariant numbers unless visiting_param changes
+        self._factor2 = np.exp((4.0 - self._visiting_param) * np.log(
+            self._visiting_param - 1.0))
+        self._factor3 = np.exp((2.0 - self._visiting_param) * np.log(2.0)
+                               / (self._visiting_param - 1.0))
+        self._factor4_p = np.sqrt(np.pi) * self._factor2 / (self._factor3 * (
+            3.0 - self._visiting_param))
+
+        self._factor5 = 1.0 / (self._visiting_param - 1.0) - 0.5
+        self._d1 = 2.0 - self._factor5
+        self._factor6 = np.pi * (1.0 - self._factor5) / np.sin(
+            np.pi * (1.0 - self._factor5)) / np.exp(gammaln(self._d1))
+
+    def visiting(self, x, step, temperature):
+        """ Based on the step in the strategy chain, new coordinates are
+        generated by changing all components is the same time or only
+        one of them, the new values are computed with visit_fn method
+        """
+        dim = x.size
+        if step < dim:
+            # Changing all coordinates with a new visiting value
+            visits = self.visit_fn(temperature, dim)
+            upper_sample, lower_sample = self.rng_gen.uniform(size=2)
+            visits[visits > self.TAIL_LIMIT] = self.TAIL_LIMIT * upper_sample
+            visits[visits < -self.TAIL_LIMIT] = -self.TAIL_LIMIT * lower_sample
+            x_visit = visits + x
+            a = x_visit - self.lower
+            b = np.fmod(a, self.bound_range) + self.bound_range
+            x_visit = np.fmod(b, self.bound_range) + self.lower
+            x_visit[np.fabs(
+                x_visit - self.lower) < self.MIN_VISIT_BOUND] += 1.e-10
+        else:
+            # Changing only one coordinate at a time based on strategy
+            # chain step
+            x_visit = np.copy(x)
+            visit = self.visit_fn(temperature, 1)[0]
+            if visit > self.TAIL_LIMIT:
+                visit = self.TAIL_LIMIT * self.rng_gen.uniform()
+            elif visit < -self.TAIL_LIMIT:
+                visit = -self.TAIL_LIMIT * self.rng_gen.uniform()
+            index = step - dim
+            x_visit[index] = visit + x[index]
+            a = x_visit[index] - self.lower[index]
+            b = np.fmod(a, self.bound_range[index]) + self.bound_range[index]
+            x_visit[index] = np.fmod(b, self.bound_range[
+                index]) + self.lower[index]
+            if np.fabs(x_visit[index] - self.lower[
+                    index]) < self.MIN_VISIT_BOUND:
+                x_visit[index] += self.MIN_VISIT_BOUND
+        return x_visit
+
+    def visit_fn(self, temperature, dim):
+        """ Formula Visita from p. 405 of reference [2] """
+        x, y = self.rng_gen.normal(size=(dim, 2)).T
+
+        factor1 = np.exp(np.log(temperature) / (self._visiting_param - 1.0))
+        factor4 = self._factor4_p * factor1
+
+        # sigmax
+        x *= np.exp(-(self._visiting_param - 1.0) * np.log(
+            self._factor6 / factor4) / (3.0 - self._visiting_param))
+
+        den = np.exp((self._visiting_param - 1.0) * np.log(np.fabs(y)) /
+                     (3.0 - self._visiting_param))
+
+        return x / den
+
+
+class EnergyState:
+    """
+    Class used to record the energy state. At any time, it knows what is the
+    currently used coordinates and the most recent best location.
+
+    Parameters
+    ----------
+    lower : array_like
+        A 1-D NumPy ndarray containing lower bounds for generating an initial
+        random components in the `reset` method.
+    upper : array_like
+        A 1-D NumPy ndarray containing upper bounds for generating an initial
+        random components in the `reset` method
+        components. Neither NaN or inf are allowed.
+    callback : callable, ``callback(x, f, context)``, optional
+        A callback function which will be called for all minima found.
+        ``x`` and ``f`` are the coordinates and function value of the
+        latest minimum found, and `context` has value in [0, 1, 2]
+    """
+    # Maximum number of trials for generating a valid starting point
+    MAX_REINIT_COUNT = 1000
+
+    def __init__(self, lower, upper, callback=None):
+        self.ebest = None
+        self.current_energy = None
+        self.current_location = None
+        self.xbest = None
+        self.lower = lower
+        self.upper = upper
+        self.callback = callback
+
+    def reset(self, func_wrapper, rng_gen, x0=None):
+        """
+        Initialize current location is the search domain. If `x0` is not
+        provided, a random location within the bounds is generated.
+        """
+        if x0 is None:
+            self.current_location = rng_gen.uniform(self.lower, self.upper,
+                                                    size=len(self.lower))
+        else:
+            self.current_location = np.copy(x0)
+        init_error = True
+        reinit_counter = 0
+        while init_error:
+            self.current_energy = func_wrapper.fun(self.current_location)
+            if self.current_energy is None:
+                raise ValueError('Objective function is returning None')
+            if not np.isfinite(self.current_energy):
+                if reinit_counter >= EnergyState.MAX_REINIT_COUNT:
+                    init_error = False
+                    message = (
+                        'Stopping algorithm because function '
+                        'create NaN or (+/-) infinity values even with '
+                        'trying new random parameters'
+                    )
+                    raise ValueError(message)
+                self.current_location = rng_gen.uniform(self.lower,
+                                                        self.upper,
+                                                        size=self.lower.size)
+                reinit_counter += 1
+            else:
+                init_error = False
+            # If first time reset, initialize ebest and xbest
+            if self.ebest is None and self.xbest is None:
+                self.ebest = self.current_energy
+                self.xbest = np.copy(self.current_location)
+            # Otherwise, we keep them in case of reannealing reset
+
+    def update_best(self, e, x, context):
+        self.ebest = e
+        self.xbest = np.copy(x)
+        if self.callback is not None:
+            val = self.callback(x, e, context)
+            if val is not None:
+                if val:
+                    return ('Callback function requested to stop early by '
+                           'returning True')
+
+    def update_current(self, e, x):
+        self.current_energy = e
+        self.current_location = np.copy(x)
+
+
+class StrategyChain:
+    """
+    Class that implements within a Markov chain the strategy for location
+    acceptance and local search decision making.
+
+    Parameters
+    ----------
+    acceptance_param : float
+        Parameter for acceptance distribution. It is used to control the
+        probability of acceptance. The lower the acceptance parameter, the
+        smaller the probability of acceptance. Default value is -5.0 with
+        a range (-1e4, -5].
+    visit_dist : VisitingDistribution
+        Instance of `VisitingDistribution` class.
+    func_wrapper : ObjectiveFunWrapper
+        Instance of `ObjectiveFunWrapper` class.
+    minimizer_wrapper: LocalSearchWrapper
+        Instance of `LocalSearchWrapper` class.
+    rand_gen : {None, int, `numpy.random.Generator`,
+                `numpy.random.RandomState`}, optional
+
+        If `seed` is None (or `np.random`), the `numpy.random.RandomState`
+        singleton is used.
+        If `seed` is an int, a new ``RandomState`` instance is used,
+        seeded with `seed`.
+        If `seed` is already a ``Generator`` or ``RandomState`` instance then
+        that instance is used.
+    energy_state: EnergyState
+        Instance of `EnergyState` class.
+
+    """
+
+    def __init__(self, acceptance_param, visit_dist, func_wrapper,
+                 minimizer_wrapper, rand_gen, energy_state):
+        # Local strategy chain minimum energy and location
+        self.emin = energy_state.current_energy
+        self.xmin = np.array(energy_state.current_location)
+        # Global optimizer state
+        self.energy_state = energy_state
+        # Acceptance parameter
+        self.acceptance_param = acceptance_param
+        # Visiting distribution instance
+        self.visit_dist = visit_dist
+        # Wrapper to objective function
+        self.func_wrapper = func_wrapper
+        # Wrapper to the local minimizer
+        self.minimizer_wrapper = minimizer_wrapper
+        self.not_improved_idx = 0
+        self.not_improved_max_idx = 1000
+        self._rand_gen = rand_gen
+        self.temperature_step = 0
+        self.K = 100 * len(energy_state.current_location)
+
+    def accept_reject(self, j, e, x_visit):
+        r = self._rand_gen.uniform()
+        pqv_temp = 1.0 - ((1.0 - self.acceptance_param) *
+            (e - self.energy_state.current_energy) / self.temperature_step)
+        if pqv_temp <= 0.:
+            pqv = 0.
+        else:
+            pqv = np.exp(np.log(pqv_temp) / (
+                1. - self.acceptance_param))
+
+        if r <= pqv:
+            # We accept the new location and update state
+            self.energy_state.update_current(e, x_visit)
+            self.xmin = np.copy(self.energy_state.current_location)
+
+        # No improvement for a long time
+        if self.not_improved_idx >= self.not_improved_max_idx:
+            if j == 0 or self.energy_state.current_energy < self.emin:
+                self.emin = self.energy_state.current_energy
+                self.xmin = np.copy(self.energy_state.current_location)
+
+    def run(self, step, temperature):
+        self.temperature_step = temperature / float(step + 1)
+        self.not_improved_idx += 1
+        for j in range(self.energy_state.current_location.size * 2):
+            if j == 0:
+                if step == 0:
+                    self.energy_state_improved = True
+                else:
+                    self.energy_state_improved = False
+            x_visit = self.visit_dist.visiting(
+                self.energy_state.current_location, j, temperature)
+            # Calling the objective function
+            e = self.func_wrapper.fun(x_visit)
+            if e < self.energy_state.current_energy:
+                # We have got a better energy value
+                self.energy_state.update_current(e, x_visit)
+                if e < self.energy_state.ebest:
+                    val = self.energy_state.update_best(e, x_visit, 0)
+                    if val is not None:
+                        if val:
+                            return val
+                    self.energy_state_improved = True
+                    self.not_improved_idx = 0
+            else:
+                # We have not improved but do we accept the new location?
+                self.accept_reject(j, e, x_visit)
+            if self.func_wrapper.nfev >= self.func_wrapper.maxfun:
+                return ('Maximum number of function call reached '
+                        'during annealing')
+        # End of StrategyChain loop
+
+    def local_search(self):
+        # Decision making for performing a local search
+        # based on strategy chain results
+        # If energy has been improved or no improvement since too long,
+        # performing a local search with the best strategy chain location
+        if self.energy_state_improved:
+            # Global energy has improved, let's see if LS improves further
+            e, x = self.minimizer_wrapper.local_search(self.energy_state.xbest,
+                                                       self.energy_state.ebest)
+            if e < self.energy_state.ebest:
+                self.not_improved_idx = 0
+                val = self.energy_state.update_best(e, x, 1)
+                if val is not None:
+                    if val:
+                        return val
+                self.energy_state.update_current(e, x)
+            if self.func_wrapper.nfev >= self.func_wrapper.maxfun:
+                return ('Maximum number of function call reached '
+                        'during local search')
+        # Check probability of a need to perform a LS even if no improvement
+        do_ls = False
+        if self.K < 90 * len(self.energy_state.current_location):
+            pls = np.exp(self.K * (
+                self.energy_state.ebest - self.energy_state.current_energy) /
+                self.temperature_step)
+            if pls >= self._rand_gen.uniform():
+                do_ls = True
+        # Global energy not improved, let's see what LS gives
+        # on the best strategy chain location
+        if self.not_improved_idx >= self.not_improved_max_idx:
+            do_ls = True
+        if do_ls:
+            e, x = self.minimizer_wrapper.local_search(self.xmin, self.emin)
+            self.xmin = np.copy(x)
+            self.emin = e
+            self.not_improved_idx = 0
+            self.not_improved_max_idx = self.energy_state.current_location.size
+            if e < self.energy_state.ebest:
+                val = self.energy_state.update_best(
+                    self.emin, self.xmin, 2)
+                if val is not None:
+                    if val:
+                        return val
+                self.energy_state.update_current(e, x)
+            if self.func_wrapper.nfev >= self.func_wrapper.maxfun:
+                return ('Maximum number of function call reached '
+                        'during dual annealing')
+
+
+class ObjectiveFunWrapper:
+
+    def __init__(self, func, maxfun=1e7, *args):
+        self.func = func
+        self.args = args
+        # Number of objective function evaluations
+        self.nfev = 0
+        # Number of gradient function evaluation if used
+        self.ngev = 0
+        # Number of hessian of the objective function if used
+        self.nhev = 0
+        self.maxfun = maxfun
+
+    def fun(self, x):
+        self.nfev += 1
+        return self.func(x, *self.args)
+
+
+class LocalSearchWrapper:
+    """
+    Class used to wrap around the minimizer used for local search
+    Default local minimizer is SciPy minimizer L-BFGS-B
+    """
+
+    LS_MAXITER_RATIO = 6
+    LS_MAXITER_MIN = 100
+    LS_MAXITER_MAX = 1000
+
+    def __init__(self, search_bounds, func_wrapper, *args, **kwargs):
+        self.func_wrapper = func_wrapper
+        self.kwargs = kwargs
+        self.jac = self.kwargs.get('jac', None)
+        self.hess = self.kwargs.get('hess', None)
+        self.hessp = self.kwargs.get('hessp', None)
+        self.kwargs.pop("args", None)
+        self.minimizer = minimize
+        bounds_list = list(zip(*search_bounds))
+        self.lower = np.array(bounds_list[0])
+        self.upper = np.array(bounds_list[1])
+
+        # If no minimizer specified, use SciPy minimize with 'L-BFGS-B' method
+        if not self.kwargs:
+            n = len(self.lower)
+            ls_max_iter = min(max(n * self.LS_MAXITER_RATIO,
+                                  self.LS_MAXITER_MIN),
+                              self.LS_MAXITER_MAX)
+            self.kwargs['method'] = 'L-BFGS-B'
+            self.kwargs['options'] = {
+                'maxiter': ls_max_iter,
+            }
+            self.kwargs['bounds'] = list(zip(self.lower, self.upper))
+        else:
+            if callable(self.jac):
+                def wrapped_jac(x):
+                    return self.jac(x, *args)
+                self.kwargs['jac'] = wrapped_jac
+            if callable(self.hess):
+                def wrapped_hess(x):
+                    return self.hess(x, *args)
+                self.kwargs['hess'] = wrapped_hess
+            if callable(self.hessp):
+                def wrapped_hessp(x, p):
+                    return self.hessp(x, p, *args)
+                self.kwargs['hessp'] = wrapped_hessp
+
+    def local_search(self, x, e):
+        # Run local search from the given x location where energy value is e
+        x_tmp = np.copy(x)
+        mres = self.minimizer(self.func_wrapper.fun, x, **self.kwargs)
+        if 'njev' in mres:
+            self.func_wrapper.ngev += mres.njev
+        if 'nhev' in mres:
+            self.func_wrapper.nhev += mres.nhev
+        # Check if is valid value
+        is_finite = np.all(np.isfinite(mres.x)) and np.isfinite(mres.fun)
+        in_bounds = np.all(mres.x >= self.lower) and np.all(
+            mres.x <= self.upper)
+        is_valid = is_finite and in_bounds
+
+        # Use the new point only if it is valid and return a better results
+        if is_valid and mres.fun < e:
+            return mres.fun, mres.x
+        else:
+            return e, x_tmp
+
+
+@_transition_to_rng("seed", position_num=10)
+def dual_annealing(func, bounds, args=(), maxiter=1000,
+                   minimizer_kwargs=None, initial_temp=5230.,
+                   restart_temp_ratio=2.e-5, visit=2.62, accept=-5.0,
+                   maxfun=1e7, rng=None, no_local_search=False,
+                   callback=None, x0=None):
+    """
+    Find the global minimum of a function using Dual Annealing.
+
+    Parameters
+    ----------
+    func : callable
+        The objective function to be minimized. Must be in the form
+        ``f(x, *args)``, where ``x`` is the argument in the form of a 1-D array
+        and ``args`` is a  tuple of any additional fixed parameters needed to
+        completely specify the function.
+    bounds : sequence or `Bounds`
+        Bounds for variables. There are two ways to specify the bounds:
+
+        1. Instance of `Bounds` class.
+        2. Sequence of ``(min, max)`` pairs for each element in `x`.
+
+    args : tuple, optional
+        Any additional fixed parameters needed to completely specify the
+        objective function.
+    maxiter : int, optional
+        The maximum number of global search iterations. Default value is 1000.
+    minimizer_kwargs : dict, optional
+        Keyword arguments to be passed to the local minimizer
+        (`minimize`). An important option could be ``method`` for the minimizer
+        method to use.
+        If no keyword arguments are provided, the local minimizer defaults to
+        'L-BFGS-B' and uses the already supplied bounds. If `minimizer_kwargs`
+        is specified, then the dict must contain all parameters required to
+        control the local minimization. `args` is ignored in this dict, as it is
+        passed automatically. `bounds` is not automatically passed on to the
+        local minimizer as the method may not support them.
+    initial_temp : float, optional
+        The initial temperature, use higher values to facilitates a wider
+        search of the energy landscape, allowing dual_annealing to escape
+        local minima that it is trapped in. Default value is 5230. Range is
+        (0.01, 5.e4].
+    restart_temp_ratio : float, optional
+        During the annealing process, temperature is decreasing, when it
+        reaches ``initial_temp * restart_temp_ratio``, the reannealing process
+        is triggered. Default value of the ratio is 2e-5. Range is (0, 1).
+    visit : float, optional
+        Parameter for visiting distribution. Default value is 2.62. Higher
+        values give the visiting distribution a heavier tail, this makes
+        the algorithm jump to a more distant region. The value range is (1, 3].
+    accept : float, optional
+        Parameter for acceptance distribution. It is used to control the
+        probability of acceptance. The lower the acceptance parameter, the
+        smaller the probability of acceptance. Default value is -5.0 with
+        a range (-1e4, -5].
+    maxfun : int, optional
+        Soft limit for the number of objective function calls. If the
+        algorithm is in the middle of a local search, this number will be
+        exceeded, the algorithm will stop just after the local search is
+        done. Default value is 1e7.
+    rng : `numpy.random.Generator`, optional
+        Pseudorandom number generator state. When `rng` is None, a new
+        `numpy.random.Generator` is created using entropy from the
+        operating system. Types other than `numpy.random.Generator` are
+        passed to `numpy.random.default_rng` to instantiate a `Generator`.
+
+        Specify `rng` for repeatable minimizations. The random numbers
+        generated only affect the visiting distribution function
+        and new coordinates generation.
+    no_local_search : bool, optional
+        If `no_local_search` is set to True, a traditional Generalized
+        Simulated Annealing will be performed with no local search
+        strategy applied.
+    callback : callable, optional
+        A callback function with signature ``callback(x, f, context)``,
+        which will be called for all minima found.
+        ``x`` and ``f`` are the coordinates and function value of the
+        latest minimum found, and ``context`` has one of the following
+        values:
+
+        - ``0``: minimum detected in the annealing process.
+        - ``1``: detection occurred in the local search process.
+        - ``2``: detection done in the dual annealing process.
+
+        If the callback implementation returns True, the algorithm will stop.
+    x0 : ndarray, shape(n,), optional
+        Coordinates of a single N-D starting point.
+
+    Returns
+    -------
+    res : OptimizeResult
+        The optimization result represented as a `OptimizeResult` object.
+        Important attributes are: ``x`` the solution array, ``fun`` the value
+        of the function at the solution, and ``message`` which describes the
+        cause of the termination.
+        See `OptimizeResult` for a description of other attributes.
+
+    Notes
+    -----
+    This function implements the Dual Annealing optimization. This stochastic
+    approach derived from [3]_ combines the generalization of CSA (Classical
+    Simulated Annealing) and FSA (Fast Simulated Annealing) [1]_ [2]_ coupled
+    to a strategy for applying a local search on accepted locations [4]_.
+    An alternative implementation of this same algorithm is described in [5]_
+    and benchmarks are presented in [6]_. This approach introduces an advanced
+    method to refine the solution found by the generalized annealing
+    process. This algorithm uses a distorted Cauchy-Lorentz visiting
+    distribution, with its shape controlled by the parameter :math:`q_{v}`
+
+    .. math::
+
+        g_{q_{v}}(\\Delta x(t)) \\propto \\frac{ \\
+        \\left[T_{q_{v}}(t) \\right]^{-\\frac{D}{3-q_{v}}}}{ \\
+        \\left[{1+(q_{v}-1)\\frac{(\\Delta x(t))^{2}} { \\
+        \\left[T_{q_{v}}(t)\\right]^{\\frac{2}{3-q_{v}}}}}\\right]^{ \\
+        \\frac{1}{q_{v}-1}+\\frac{D-1}{2}}}
+
+    Where :math:`t` is the artificial time. This visiting distribution is used
+    to generate a trial jump distance :math:`\\Delta x(t)` of variable
+    :math:`x(t)` under artificial temperature :math:`T_{q_{v}}(t)`.
+
+    From the starting point, after calling the visiting distribution
+    function, the acceptance probability is computed as follows:
+
+    .. math::
+
+        p_{q_{a}} = \\min{\\{1,\\left[1-(1-q_{a}) \\beta \\Delta E \\right]^{ \\
+        \\frac{1}{1-q_{a}}}\\}}
+
+    Where :math:`q_{a}` is a acceptance parameter. For :math:`q_{a}<1`, zero
+    acceptance probability is assigned to the cases where
+
+    .. math::
+
+        [1-(1-q_{a}) \\beta \\Delta E] < 0
+
+    The artificial temperature :math:`T_{q_{v}}(t)` is decreased according to
+
+    .. math::
+
+        T_{q_{v}}(t) = T_{q_{v}}(1) \\frac{2^{q_{v}-1}-1}{\\left( \\
+        1 + t\\right)^{q_{v}-1}-1}
+
+    Where :math:`q_{v}` is the visiting parameter.
+
+    .. versionadded:: 1.2.0
+
+    References
+    ----------
+    .. [1] Tsallis C. Possible generalization of Boltzmann-Gibbs
+        statistics. Journal of Statistical Physics, 52, 479-487 (1988).
+    .. [2] Tsallis C, Stariolo DA. Generalized Simulated Annealing.
+        Physica A, 233, 395-406 (1996).
+    .. [3] Xiang Y, Sun DY, Fan W, Gong XG. Generalized Simulated
+        Annealing Algorithm and Its Application to the Thomson Model.
+        Physics Letters A, 233, 216-220 (1997).
+    .. [4] Xiang Y, Gong XG. Efficiency of Generalized Simulated
+        Annealing. Physical Review E, 62, 4473 (2000).
+    .. [5] Xiang Y, Gubian S, Suomela B, Hoeng J. Generalized
+        Simulated Annealing for Efficient Global Optimization: the GenSA
+        Package for R. The R Journal, Volume 5/1 (2013).
+    .. [6] Mullen, K. Continuous Global Optimization in R. Journal of
+        Statistical Software, 60(6), 1 - 45, (2014).
+        :doi:`10.18637/jss.v060.i06`
+
+    Examples
+    --------
+    The following example is a 10-D problem, with many local minima.
+    The function involved is called Rastrigin
+    (https://en.wikipedia.org/wiki/Rastrigin_function)
+
+    >>> import numpy as np
+    >>> from scipy.optimize import dual_annealing
+    >>> func = lambda x: np.sum(x*x - 10*np.cos(2*np.pi*x)) + 10*np.size(x)
+    >>> lw = [-5.12] * 10
+    >>> up = [5.12] * 10
+    >>> ret = dual_annealing(func, bounds=list(zip(lw, up)))
+    >>> ret.x
+    array([-4.26437714e-09, -3.91699361e-09, -1.86149218e-09, -3.97165720e-09,
+           -6.29151648e-09, -6.53145322e-09, -3.93616815e-09, -6.55623025e-09,
+           -6.05775280e-09, -5.00668935e-09]) # random
+    >>> ret.fun
+    0.000000
+
+    """
+
+    if isinstance(bounds, Bounds):
+        bounds = new_bounds_to_old(bounds.lb, bounds.ub, len(bounds.lb))
+
+    if x0 is not None and not len(x0) == len(bounds):
+        raise ValueError('Bounds size does not match x0')
+
+    lu = list(zip(*bounds))
+    lower = np.array(lu[0])
+    upper = np.array(lu[1])
+    # Check that restart temperature ratio is correct
+    if restart_temp_ratio <= 0. or restart_temp_ratio >= 1.:
+        raise ValueError('Restart temperature ratio has to be in range (0, 1)')
+    # Checking bounds are valid
+    if (np.any(np.isinf(lower)) or np.any(np.isinf(upper)) or np.any(
+            np.isnan(lower)) or np.any(np.isnan(upper))):
+        raise ValueError('Some bounds values are inf values or nan values')
+    # Checking that bounds are consistent
+    if not np.all(lower < upper):
+        raise ValueError('Bounds are not consistent min < max')
+    # Checking that bounds are the same length
+    if not len(lower) == len(upper):
+        raise ValueError('Bounds do not have the same dimensions')
+
+    # Wrapper for the objective function
+    func_wrapper = ObjectiveFunWrapper(func, maxfun, *args)
+
+    # minimizer_kwargs has to be a dict, not None
+    minimizer_kwargs = minimizer_kwargs or {}
+
+    minimizer_wrapper = LocalSearchWrapper(
+        bounds, func_wrapper, *args, **minimizer_kwargs)
+
+    # Initialization of random Generator for reproducible runs if rng provided
+    rng_gen = check_random_state(rng)
+    # Initialization of the energy state
+    energy_state = EnergyState(lower, upper, callback)
+    energy_state.reset(func_wrapper, rng_gen, x0)
+    # Minimum value of annealing temperature reached to perform
+    # re-annealing
+    temperature_restart = initial_temp * restart_temp_ratio
+    # VisitingDistribution instance
+    visit_dist = VisitingDistribution(lower, upper, visit, rng_gen)
+    # Strategy chain instance
+    strategy_chain = StrategyChain(accept, visit_dist, func_wrapper,
+                                   minimizer_wrapper, rng_gen, energy_state)
+    need_to_stop = False
+    iteration = 0
+    message = []
+    # OptimizeResult object to be returned
+    optimize_res = OptimizeResult()
+    optimize_res.success = True
+    optimize_res.status = 0
+
+    t1 = np.exp((visit - 1) * np.log(2.0)) - 1.0
+    # Run the search loop
+    while not need_to_stop:
+        for i in range(maxiter):
+            # Compute temperature for this step
+            s = float(i) + 2.0
+            t2 = np.exp((visit - 1) * np.log(s)) - 1.0
+            temperature = initial_temp * t1 / t2
+            if iteration >= maxiter:
+                message.append("Maximum number of iteration reached")
+                need_to_stop = True
+                break
+            # Need a re-annealing process?
+            if temperature < temperature_restart:
+                energy_state.reset(func_wrapper, rng_gen)
+                break
+            # starting strategy chain
+            val = strategy_chain.run(i, temperature)
+            if val is not None:
+                message.append(val)
+                need_to_stop = True
+                optimize_res.success = False
+                break
+            # Possible local search at the end of the strategy chain
+            if not no_local_search:
+                val = strategy_chain.local_search()
+                if val is not None:
+                    message.append(val)
+                    need_to_stop = True
+                    optimize_res.success = False
+                    break
+            iteration += 1
+
+    # Setting the OptimizeResult values
+    optimize_res.x = energy_state.xbest
+    optimize_res.fun = energy_state.ebest
+    optimize_res.nit = iteration
+    optimize_res.nfev = func_wrapper.nfev
+    optimize_res.njev = func_wrapper.ngev
+    optimize_res.nhev = func_wrapper.nhev
+    optimize_res.message = message
+    return optimize_res

venv/lib/python3.13/site-packages/scipy/optimize/_elementwise.py

@@ -0,0 +1,798 @@
+from scipy.optimize._bracket import _bracket_root, _bracket_minimum
+from scipy.optimize._chandrupatla import _chandrupatla, _chandrupatla_minimize
+from scipy._lib._util import _RichResult
+
+
+def find_root(f, init, /, *, args=(), tolerances=None, maxiter=None, callback=None):
+    """Find the root of a monotonic, real-valued function of a real variable.
+
+    For each element of the output of `f`, `find_root` seeks the scalar
+    root that makes the element 0. This function currently uses Chandrupatla's
+    bracketing algorithm [1]_ and therefore requires argument `init` to
+    provide a bracket around the root: the function values at the two endpoints
+    must have opposite signs.
+
+    Provided a valid bracket, `find_root` is guaranteed to converge to a solution
+    that satisfies the provided `tolerances` if the function is continuous within
+    the bracket.
+
+    This function works elementwise when `init` and `args` contain (broadcastable)
+    arrays.
+
+    Parameters
+    ----------
+    f : callable
+        The function whose root is desired. The signature must be::
+
+            f(x: array, *args) -> array
+
+        where each element of ``x`` is a finite real and ``args`` is a tuple,
+        which may contain an arbitrary number of arrays that are broadcastable
+        with ``x``.
+
+        `f` must be an elementwise function: each element ``f(x)[i]``
+        must equal ``f(x[i])`` for all indices ``i``. It must not mutate the
+        array ``x`` or the arrays in ``args``.
+
+        `find_root` seeks an array ``x`` such that ``f(x)`` is an array of zeros.
+    init : 2-tuple of float array_like
+        The lower and upper endpoints of a bracket surrounding the desired root.
+        A bracket is valid if arrays ``xl, xr = init`` satisfy ``xl < xr`` and
+        ``sign(f(xl)) == -sign(f(xr))`` elementwise. Arrays be broadcastable with
+        one another and `args`.
+    args : tuple of array_like, optional
+        Additional positional array arguments to be passed to `f`. Arrays
+        must be broadcastable with one another and the arrays of `init`.
+        If the callable for which the root is desired requires arguments that are
+        not broadcastable with `x`, wrap that callable with `f` such that `f`
+        accepts only `x` and broadcastable ``*args``.
+    tolerances : dictionary of floats, optional
+        Absolute and relative tolerances on the root and function value.
+        Valid keys of the dictionary are:
+
+        - ``xatol`` - absolute tolerance on the root
+        - ``xrtol`` - relative tolerance on the root
+        - ``fatol`` - absolute tolerance on the function value
+        - ``frtol`` - relative tolerance on the function value
+
+        See Notes for default values and explicit termination conditions.
+    maxiter : int, optional
+        The maximum number of iterations of the algorithm to perform.
+        The default is the maximum possible number of bisections within
+        the (normal) floating point numbers of the relevant dtype.
+    callback : callable, optional
+        An optional user-supplied function to be called before the first
+        iteration and after each iteration.
+        Called as ``callback(res)``, where ``res`` is a ``_RichResult``
+        similar to that returned by `find_root` (but containing the current
+        iterate's values of all variables). If `callback` raises a
+        ``StopIteration``, the algorithm will terminate immediately and
+        `find_root` will return a result. `callback` must not mutate
+        `res` or its attributes.
+
+    Returns
+    -------
+    res : _RichResult
+        An object similar to an instance of `scipy.optimize.OptimizeResult` with the
+        following attributes. The descriptions are written as though the values will
+        be scalars; however, if `f` returns an array, the outputs will be
+        arrays of the same shape.
+
+        success : bool array
+            ``True`` where the algorithm terminated successfully (status ``0``);
+            ``False`` otherwise.
+        status : int array
+            An integer representing the exit status of the algorithm.
+
+            - ``0`` : The algorithm converged to the specified tolerances.
+            - ``-1`` : The initial bracket was invalid.
+            - ``-2`` : The maximum number of iterations was reached.
+            - ``-3`` : A non-finite value was encountered.
+            - ``-4`` : Iteration was terminated by `callback`.
+            - ``1`` : The algorithm is proceeding normally (in `callback` only).
+
+        x : float array
+            The root of the function, if the algorithm terminated successfully.
+        f_x : float array
+            The value of `f` evaluated at `x`.
+        nfev : int array
+            The number of abscissae at which `f` was evaluated to find the root.
+            This is distinct from the number of times `f` is *called* because the
+            the function may evaluated at multiple points in a single call.
+        nit : int array
+            The number of iterations of the algorithm that were performed.
+        bracket : tuple of float arrays
+            The lower and upper endpoints of the final bracket.
+        f_bracket : tuple of float arrays
+            The value of `f` evaluated at the lower and upper endpoints of the
+            bracket.
+
+    Notes
+    -----
+    Implemented based on Chandrupatla's original paper [1]_.
+
+    Let:
+
+    -  ``a, b = init`` be the left and right endpoints of the initial bracket,
+    - ``xl`` and ``xr`` be the left and right endpoints of the final bracket,
+    - ``xmin = xl if abs(f(xl)) <= abs(f(xr)) else xr`` be the final bracket
+      endpoint with the smaller function value, and
+    - ``fmin0 = min(f(a), f(b))`` be the minimum of the two values of the
+      function evaluated at the initial bracket endpoints.
+
+    Then the algorithm is considered to have converged when
+
+    - ``abs(xr - xl) < xatol + abs(xmin) * xrtol`` or
+    - ``fun(xmin) <= fatol + abs(fmin0) * frtol``.
+
+    This is equivalent to the termination condition described in [1]_ with
+    ``xrtol = 4e-10``, ``xatol = 1e-5``, and ``fatol = frtol = 0``.
+    However, the default values of the `tolerances` dictionary are
+    ``xatol = 4*tiny``, ``xrtol = 4*eps``, ``frtol = 0``, and ``fatol = tiny``,
+    where ``eps`` and ``tiny`` are the precision and smallest normal number
+    of the result ``dtype`` of function inputs and outputs.
+
+    References
+    ----------
+
+    .. [1] Chandrupatla, Tirupathi R.
+        "A new hybrid quadratic/bisection algorithm for finding the zero of a
+        nonlinear function without using derivatives".
+        Advances in Engineering Software, 28(3), 145-149.
+        https://doi.org/10.1016/s0965-9978(96)00051-8
+
+    See Also
+    --------
+    bracket_root
+
+    Examples
+    --------
+    Suppose we wish to find the root of the following function.
+
+    >>> def f(x, c=5):
+    ...     return x**3 - 2*x - c
+
+    First, we must find a valid bracket. The function is not monotonic,
+    but `bracket_root` may be able to provide a bracket.
+
+    >>> from scipy.optimize import elementwise
+    >>> res_bracket = elementwise.bracket_root(f, 0)
+    >>> res_bracket.success
+    True
+    >>> res_bracket.bracket
+    (2.0, 4.0)
+
+    Indeed, the values of the function at the bracket endpoints have
+    opposite signs.
+
+    >>> res_bracket.f_bracket
+    (-1.0, 51.0)
+
+    Once we have a valid bracket, `find_root` can be used to provide
+    a precise root.
+
+    >>> res_root = elementwise.find_root(f, res_bracket.bracket)
+    >>> res_root.x
+    2.0945514815423265
+
+    The final bracket is only a few ULPs wide, so the error between
+    this value and the true root cannot be much smaller within values
+    that are representable in double precision arithmetic.
+
+    >>> import numpy as np
+    >>> xl, xr = res_root.bracket
+    >>> (xr - xl) / np.spacing(xl)
+    2.0
+    >>> res_root.f_bracket
+    (-8.881784197001252e-16, 9.769962616701378e-15)
+
+    `bracket_root` and `find_root` accept arrays for most arguments.
+    For instance, to find the root for a few values of the parameter ``c``
+    at once:
+
+    >>> c = np.asarray([3, 4, 5])
+    >>> res_bracket = elementwise.bracket_root(f, 0, args=(c,))
+    >>> res_bracket.bracket
+    (array([1., 1., 2.]), array([2., 2., 4.]))
+    >>> res_root = elementwise.find_root(f, res_bracket.bracket, args=(c,))
+    >>> res_root.x
+    array([1.8932892 , 2.        , 2.09455148])
+
+    """
+
+    def reformat_result(res_in):
+        res_out = _RichResult()
+        res_out.status = res_in.status
+        res_out.success = res_in.success
+        res_out.x = res_in.x
+        res_out.f_x = res_in.fun
+        res_out.nfev = res_in.nfev
+        res_out.nit = res_in.nit
+        res_out.bracket = (res_in.xl, res_in.xr)
+        res_out.f_bracket = (res_in.fl, res_in.fr)
+        res_out._order_keys = ['success', 'status', 'x', 'f_x',
+                               'nfev', 'nit', 'bracket', 'f_bracket']
+        return res_out
+
+    xl, xr = init
+    default_tolerances = dict(xatol=None, xrtol=None, fatol=None, frtol=0)
+    tolerances = {} if tolerances is None else tolerances
+    default_tolerances.update(tolerances)
+    tolerances = default_tolerances
+
+    if callable(callback):
+        def _callback(res):
+            return callback(reformat_result(res))
+    else:
+        _callback = callback
+
+    res = _chandrupatla(f, xl, xr, args=args, **tolerances,
+                        maxiter=maxiter, callback=_callback)
+    return reformat_result(res)
+
+
+def find_minimum(f, init, /, *, args=(), tolerances=None, maxiter=100, callback=None):
+    """Find the minimum of an unimodal, real-valued function of a real variable.
+
+    For each element of the output of `f`, `find_minimum` seeks the scalar minimizer
+    that minimizes the element. This function currently uses Chandrupatla's
+    bracketing minimization algorithm [1]_ and therefore requires argument `init`
+    to provide a three-point minimization bracket: ``x1 < x2 < x3`` such that
+    ``func(x1) >= func(x2) <= func(x3)``, where one of the inequalities is strict.
+
+    Provided a valid bracket, `find_minimum` is guaranteed to converge to a local
+    minimum that satisfies the provided `tolerances` if the function is continuous
+    within the bracket.
+
+    This function works elementwise when `init` and `args` contain (broadcastable)
+    arrays.
+
+    Parameters
+    ----------
+    f : callable
+        The function whose minimizer is desired. The signature must be::
+
+            f(x: array, *args) -> array
+
+        where each element of ``x`` is a finite real and ``args`` is a tuple,
+        which may contain an arbitrary number of arrays that are broadcastable
+        with ``x``.
+
+        `f` must be an elementwise function: each element ``f(x)[i]``
+        must equal ``f(x[i])`` for all indices ``i``. It must not mutate the
+        array ``x`` or the arrays in ``args``.
+
+        `find_minimum` seeks an array ``x`` such that ``f(x)`` is an array of
+        local minima.
+    init : 3-tuple of float array_like
+        The abscissae of a standard scalar minimization bracket. A bracket is
+        valid if arrays ``x1, x2, x3 = init`` satisfy ``x1 < x2 < x3`` and
+        ``func(x1) >= func(x2) <= func(x3)``, where one of the inequalities
+        is strict. Arrays must be broadcastable with one another and the arrays
+        of `args`.
+    args : tuple of array_like, optional
+        Additional positional array arguments to be passed to `f`. Arrays
+        must be broadcastable with one another and the arrays of `init`.
+        If the callable for which the root is desired requires arguments that are
+        not broadcastable with `x`, wrap that callable with `f` such that `f`
+        accepts only `x` and broadcastable ``*args``.
+    tolerances : dictionary of floats, optional
+        Absolute and relative tolerances on the root and function value.
+        Valid keys of the dictionary are:
+
+        - ``xatol`` - absolute tolerance on the root
+        - ``xrtol`` - relative tolerance on the root
+        - ``fatol`` - absolute tolerance on the function value
+        - ``frtol`` - relative tolerance on the function value
+
+        See Notes for default values and explicit termination conditions.
+    maxiter : int, default: 100
+        The maximum number of iterations of the algorithm to perform.
+    callback : callable, optional
+        An optional user-supplied function to be called before the first
+        iteration and after each iteration.
+        Called as ``callback(res)``, where ``res`` is a ``_RichResult``
+        similar to that returned by `find_minimum` (but containing the current
+        iterate's values of all variables). If `callback` raises a
+        ``StopIteration``, the algorithm will terminate immediately and
+        `find_root` will return a result. `callback` must not mutate
+        `res` or its attributes.
+
+    Returns
+    -------
+    res : _RichResult
+        An object similar to an instance of `scipy.optimize.OptimizeResult` with the
+        following attributes. The descriptions are written as though the values will
+        be scalars; however, if `f` returns an array, the outputs will be
+        arrays of the same shape.
+
+        success : bool array
+            ``True`` where the algorithm terminated successfully (status ``0``);
+            ``False`` otherwise.
+        status : int array
+            An integer representing the exit status of the algorithm.
+
+            - ``0`` : The algorithm converged to the specified tolerances.
+            - ``-1`` : The algorithm encountered an invalid bracket.
+            - ``-2`` : The maximum number of iterations was reached.
+            - ``-3`` : A non-finite value was encountered.
+            - ``-4`` : Iteration was terminated by `callback`.
+            - ``1`` : The algorithm is proceeding normally (in `callback` only).
+
+        x : float array
+            The minimizer of the function, if the algorithm terminated successfully.
+        f_x : float array
+            The value of `f` evaluated at `x`.
+        nfev : int array
+            The number of abscissae at which `f` was evaluated to find the root.
+            This is distinct from the number of times `f` is *called* because the
+            the function may evaluated at multiple points in a single call.
+        nit : int array
+            The number of iterations of the algorithm that were performed.
+        bracket : tuple of float arrays
+            The final three-point bracket.
+        f_bracket : tuple of float arrays
+            The value of `f` evaluated at the bracket points.
+
+    Notes
+    -----
+    Implemented based on Chandrupatla's original paper [1]_.
+
+    If ``xl < xm < xr`` are the points of the bracket and ``fl >= fm <= fr``
+    (where one of the inequalities is strict) are the values of `f` evaluated
+    at those points, then the algorithm is considered to have converged when:
+
+    - ``abs(xr - xm)/2 <= abs(xm)*xrtol + xatol`` or
+    - ``(fl - 2*fm + fr)/2 <= abs(fm)*frtol + fatol``.
+
+    The default value of `xrtol` is the square root of the precision of the
+    appropriate dtype, and ``xatol = fatol = frtol`` is the smallest normal
+    number of the appropriate dtype.
+
+    References
+    ----------
+
+    .. [1] Chandrupatla, Tirupathi R. (1998).
+        "An efficient quadratic fit-sectioning algorithm for minimization
+        without derivatives".
+        Computer Methods in Applied Mechanics and Engineering, 152 (1-2),
+        211-217. https://doi.org/10.1016/S0045-7825(97)00190-4
+
+    See Also
+    --------
+    bracket_minimum
+
+    Examples
+    --------
+    Suppose we wish to minimize the following function.
+
+    >>> def f(x, c=1):
+    ...     return (x - c)**2 + 2
+
+    First, we must find a valid bracket. The function is unimodal,
+    so `bracket_minium` will easily find a bracket.
+
+    >>> from scipy.optimize import elementwise
+    >>> res_bracket = elementwise.bracket_minimum(f, 0)
+    >>> res_bracket.success
+    True
+    >>> res_bracket.bracket
+    (0.0, 0.5, 1.5)
+
+    Indeed, the bracket points are ordered and the function value
+    at the middle bracket point is less than at the surrounding
+    points.
+
+    >>> xl, xm, xr = res_bracket.bracket
+    >>> fl, fm, fr = res_bracket.f_bracket
+    >>> (xl < xm < xr) and (fl > fm <= fr)
+    True
+
+    Once we have a valid bracket, `find_minimum` can be used to provide
+    an estimate of the minimizer.
+
+    >>> res_minimum = elementwise.find_minimum(f, res_bracket.bracket)
+    >>> res_minimum.x
+    1.0000000149011612
+
+    The function value changes by only a few ULPs within the bracket, so
+    the minimizer cannot be determined much more precisely by evaluating
+    the function alone (i.e. we would need its derivative to do better).
+
+    >>> import numpy as np
+    >>> fl, fm, fr = res_minimum.f_bracket
+    >>> (fl - fm) / np.spacing(fm), (fr - fm) / np.spacing(fm)
+    (0.0, 2.0)
+
+    Therefore, a precise minimum of the function is given by:
+
+    >>> res_minimum.f_x
+    2.0
+
+    `bracket_minimum` and `find_minimum` accept arrays for most arguments.
+    For instance, to find the minimizers and minima for a few values of the
+    parameter ``c`` at once:
+
+    >>> c = np.asarray([1, 1.5, 2])
+    >>> res_bracket = elementwise.bracket_minimum(f, 0, args=(c,))
+    >>> res_bracket.bracket
+    (array([0. , 0.5, 0.5]), array([0.5, 1.5, 1.5]), array([1.5, 2.5, 2.5]))
+    >>> res_minimum = elementwise.find_minimum(f, res_bracket.bracket, args=(c,))
+    >>> res_minimum.x
+    array([1.00000001, 1.5       , 2.        ])
+    >>> res_minimum.f_x
+    array([2., 2., 2.])
+
+    """
+
+    def reformat_result(res_in):
+        res_out = _RichResult()
+        res_out.status = res_in.status
+        res_out.success = res_in.success
+        res_out.x = res_in.x
+        res_out.f_x = res_in.fun
+        res_out.nfev = res_in.nfev
+        res_out.nit = res_in.nit
+        res_out.bracket = (res_in.xl, res_in.xm, res_in.xr)
+        res_out.f_bracket = (res_in.fl, res_in.fm, res_in.fr)
+        res_out._order_keys = ['success', 'status', 'x', 'f_x',
+                               'nfev', 'nit', 'bracket', 'f_bracket']
+        return res_out
+
+    xl, xm, xr = init
+    default_tolerances = dict(xatol=None, xrtol=None, fatol=None, frtol=None)
+    tolerances = {} if tolerances is None else tolerances
+    default_tolerances.update(tolerances)
+    tolerances = default_tolerances
+
+    if callable(callback):
+        def _callback(res):
+            return callback(reformat_result(res))
+    else:
+        _callback = callback
+
+    res = _chandrupatla_minimize(f, xl, xm, xr, args=args, **tolerances,
+                                 maxiter=maxiter, callback=_callback)
+    return reformat_result(res)
+
+
+def bracket_root(f, xl0, xr0=None, *, xmin=None, xmax=None, factor=None, args=(),
+                 maxiter=1000):
+    """Bracket the root of a monotonic, real-valued function of a real variable.
+
+    For each element of the output of `f`, `bracket_root` seeks the scalar
+    bracket endpoints ``xl`` and ``xr`` such that ``sign(f(xl)) == -sign(f(xr))``
+    elementwise.
+
+    The function is guaranteed to find a valid bracket if the function is monotonic,
+    but it may find a bracket under other conditions.
+
+    This function works elementwise when `xl0`, `xr0`, `xmin`, `xmax`, `factor`, and
+    the elements of `args` are (mutually broadcastable) arrays.
+
+    Parameters
+    ----------
+    f : callable
+        The function for which the root is to be bracketed. The signature must be::
+
+            f(x: array, *args) -> array
+
+        where each element of ``x`` is a finite real and ``args`` is a tuple,
+        which may contain an arbitrary number of arrays that are broadcastable
+        with ``x``.
+
+        `f` must be an elementwise function: each element ``f(x)[i]``
+        must equal ``f(x[i])`` for all indices ``i``. It must not mutate the
+        array ``x`` or the arrays in ``args``.
+    xl0, xr0: float array_like
+        Starting guess of bracket, which need not contain a root. If `xr0` is
+        not provided, ``xr0 = xl0 + 1``. Must be broadcastable with all other
+        array inputs.
+    xmin, xmax : float array_like, optional
+        Minimum and maximum allowable endpoints of the bracket, inclusive. Must
+        be broadcastable with all other array inputs.
+    factor : float array_like, default: 2
+        The factor used to grow the bracket. See Notes.
+    args : tuple of array_like, optional
+        Additional positional array arguments to be passed to `f`.
+        If the callable for which the root is desired requires arguments that are
+        not broadcastable with `x`, wrap that callable with `f` such that `f`
+        accepts only `x` and broadcastable ``*args``.
+    maxiter : int, default: 1000
+        The maximum number of iterations of the algorithm to perform.
+
+    Returns
+    -------
+    res : _RichResult
+        An object similar to an instance of `scipy.optimize.OptimizeResult` with the
+        following attributes. The descriptions are written as though the values will
+        be scalars; however, if `f` returns an array, the outputs will be
+        arrays of the same shape.
+
+        success : bool array
+            ``True`` where the algorithm terminated successfully (status ``0``);
+            ``False`` otherwise.
+        status : int array
+            An integer representing the exit status of the algorithm.
+
+            - ``0`` : The algorithm produced a valid bracket.
+            - ``-1`` : The bracket expanded to the allowable limits without success.
+            - ``-2`` : The maximum number of iterations was reached.
+            - ``-3`` : A non-finite value was encountered.
+            - ``-4`` : Iteration was terminated by `callback`.
+            - ``-5``: The initial bracket does not satisfy`xmin <= xl0 < xr0 < xmax`.
+            
+        bracket : 2-tuple of float arrays
+            The lower and upper endpoints of the bracket, if the algorithm
+            terminated successfully.
+        f_bracket : 2-tuple of float arrays
+            The values of `f` evaluated at the endpoints of ``res.bracket``,
+            respectively.
+        nfev : int array
+            The number of abscissae at which `f` was evaluated to find the root.
+            This is distinct from the number of times `f` is *called* because the
+            the function may evaluated at multiple points in a single call.
+        nit : int array
+            The number of iterations of the algorithm that were performed.
+
+    Notes
+    -----
+    This function generalizes an algorithm found in pieces throughout the
+    `scipy.stats` codebase. The strategy is to iteratively grow the bracket `(l, r)`
+    until ``f(l) < 0 < f(r)`` or ``f(r) < 0 < f(l)``. The bracket grows to the left
+    as follows.
+
+    - If `xmin` is not provided, the distance between `xl0` and `l` is iteratively
+      increased by `factor`.
+    - If `xmin` is provided, the distance between `xmin` and `l` is iteratively
+      decreased by `factor`. Note that this also *increases* the bracket size.
+
+    Growth of the bracket to the right is analogous.
+
+    Growth of the bracket in one direction stops when the endpoint is no longer
+    finite, the function value at the endpoint is no longer finite, or the
+    endpoint reaches its limiting value (`xmin` or `xmax`). Iteration terminates
+    when the bracket stops growing in both directions, the bracket surrounds
+    the root, or a root is found (by chance).
+
+    If two brackets are found - that is, a bracket is found on both sides in
+    the same iteration, the smaller of the two is returned.
+    
+    If roots of the function are found, both `xl` and `xr` are set to the
+    leftmost root.
+    
+    See Also
+    --------
+    find_root
+
+    Examples
+    --------
+    Suppose we wish to find the root of the following function.
+
+    >>> def f(x, c=5):
+    ...     return x**3 - 2*x - c
+
+    First, we must find a valid bracket. The function is not monotonic,
+    but `bracket_root` may be able to provide a bracket.
+
+    >>> from scipy.optimize import elementwise
+    >>> res_bracket = elementwise.bracket_root(f, 0)
+    >>> res_bracket.success
+    True
+    >>> res_bracket.bracket
+    (2.0, 4.0)
+
+    Indeed, the values of the function at the bracket endpoints have
+    opposite signs.
+
+    >>> res_bracket.f_bracket
+    (-1.0, 51.0)
+
+    Once we have a valid bracket, `find_root` can be used to provide
+    a precise root.
+
+    >>> res_root = elementwise.find_root(f, res_bracket.bracket)
+    >>> res_root.x
+    2.0945514815423265
+
+    `bracket_root` and `find_root` accept arrays for most arguments.
+    For instance, to find the root for a few values of the parameter ``c``
+    at once:
+
+    >>> import numpy as np
+    >>> c = np.asarray([3, 4, 5])
+    >>> res_bracket = elementwise.bracket_root(f, 0, args=(c,))
+    >>> res_bracket.bracket
+    (array([1., 1., 2.]), array([2., 2., 4.]))
+    >>> res_root = elementwise.find_root(f, res_bracket.bracket, args=(c,))
+    >>> res_root.x
+    array([1.8932892 , 2.        , 2.09455148])
+
+    """  # noqa: E501
+
+    res = _bracket_root(f, xl0, xr0=xr0, xmin=xmin, xmax=xmax, factor=factor,
+                        args=args, maxiter=maxiter)
+    res.bracket = res.xl, res.xr
+    res.f_bracket = res.fl, res.fr
+    del res.xl
+    del res.xr
+    del res.fl
+    del res.fr
+    return res
+
+
+def bracket_minimum(f, xm0, *, xl0=None, xr0=None, xmin=None, xmax=None,
+                     factor=None, args=(), maxiter=1000):
+    """Bracket the minimum of a unimodal, real-valued function of a real variable.
+
+    For each element of the output of `f`, `bracket_minimum` seeks the scalar
+    bracket points ``xl < xm < xr`` such that ``fl >= fm <= fr`` where one of the
+    inequalities is strict.
+
+    The function is guaranteed to find a valid bracket if the function is
+    strongly unimodal, but it may find a bracket under other conditions.
+
+    This function works elementwise when `xm0`, `xl0`, `xr0`, `xmin`, `xmax`, `factor`,
+    and the elements of `args` are (mutually broadcastable) arrays.
+
+    Parameters
+    ----------
+    f : callable
+        The function for which the root is to be bracketed. The signature must be::
+
+            f(x: array, *args) -> array
+
+        where each element of ``x`` is a finite real and ``args`` is a tuple,
+        which may contain an arbitrary number of arrays that are broadcastable
+        with ``x``.
+
+        `f` must be an elementwise function: each element ``f(x)[i]``
+        must equal ``f(x[i])`` for all indices ``i``. It must not mutate the
+        array ``x`` or the arrays in ``args``.
+    xm0: float array_like
+        Starting guess for middle point of bracket.
+    xl0, xr0: float array_like, optional
+        Starting guesses for left and right endpoints of the bracket. Must
+        be broadcastable with all other array inputs.
+    xmin, xmax : float array_like, optional
+        Minimum and maximum allowable endpoints of the bracket, inclusive. Must
+        be broadcastable with all other array inputs.
+    factor : float array_like, default: 2
+        The factor used to grow the bracket. See Notes.
+    args : tuple of array_like, optional
+        Additional positional array arguments to be passed to `f`.
+        If the callable for which the root is desired requires arguments that are
+        not broadcastable with `x`, wrap that callable with `f` such that `f`
+        accepts only `x` and broadcastable ``*args``.
+    maxiter : int, default: 1000
+        The maximum number of iterations of the algorithm to perform.
+
+    Returns
+    -------
+    res : _RichResult
+        An object similar to an instance of `scipy.optimize.OptimizeResult` with the
+        following attributes. The descriptions are written as though the values will
+        be scalars; however, if `f` returns an array, the outputs will be
+        arrays of the same shape.
+
+        success : bool array
+            ``True`` where the algorithm terminated successfully (status ``0``);
+            ``False`` otherwise.
+        status : int array
+            An integer representing the exit status of the algorithm.
+
+            - ``0`` : The algorithm produced a valid bracket.
+            - ``-1`` : The bracket expanded to the allowable limits. Assuming
+              unimodality, this implies the endpoint at the limit is a minimizer.
+            - ``-2`` : The maximum number of iterations was reached.
+            - ``-3`` : A non-finite value was encountered.
+            - ``-4`` : ``None`` shall pass.
+            - ``-5`` : The initial bracket does not satisfy
+              `xmin <= xl0 < xm0 < xr0 <= xmax`.
+
+        bracket : 3-tuple of float arrays
+            The left, middle, and right points of the bracket, if the algorithm
+            terminated successfully.
+        f_bracket : 3-tuple of float arrays
+            The function value at the left, middle, and right points of the bracket.
+        nfev : int array
+            The number of abscissae at which `f` was evaluated to find the root.
+            This is distinct from the number of times `f` is *called* because the
+            the function may evaluated at multiple points in a single call.
+        nit : int array
+            The number of iterations of the algorithm that were performed.
+
+    Notes
+    -----
+    Similar to `scipy.optimize.bracket`, this function seeks to find real
+    points ``xl < xm < xr`` such that ``f(xl) >= f(xm)`` and ``f(xr) >= f(xm)``,
+    where at least one of the inequalities is strict. Unlike `scipy.optimize.bracket`,
+    this function can operate in a vectorized manner on array input, so long as
+    the input arrays are broadcastable with each other. Also unlike
+    `scipy.optimize.bracket`, users may specify minimum and maximum endpoints
+    for the desired bracket.
+
+    Given an initial trio of points ``xl = xl0``, ``xm = xm0``, ``xr = xr0``,
+    the algorithm checks if these points already give a valid bracket. If not,
+    a new endpoint, ``w`` is chosen in the "downhill" direction, ``xm`` becomes the new
+    opposite endpoint, and either `xl` or `xr` becomes the new middle point,
+    depending on which direction is downhill. The algorithm repeats from here.
+
+    The new endpoint `w` is chosen differently depending on whether or not a
+    boundary `xmin` or `xmax` has been set in the downhill direction. Without
+    loss of generality, suppose the downhill direction is to the right, so that
+    ``f(xl) > f(xm) > f(xr)``. If there is no boundary to the right, then `w`
+    is chosen to be ``xr + factor * (xr - xm)`` where `factor` is controlled by
+    the user (defaults to 2.0) so that step sizes increase in geometric proportion.
+    If there is a boundary, `xmax` in this case, then `w` is chosen to be
+    ``xmax - (xmax - xr)/factor``, with steps slowing to a stop at
+    `xmax`. This cautious approach ensures that a minimum near but distinct from
+    the boundary isn't missed while also detecting whether or not the `xmax` is
+    a minimizer when `xmax` is reached after a finite number of steps.
+
+    See Also
+    --------
+    scipy.optimize.bracket
+    scipy.optimize.elementwise.find_minimum
+
+    Examples
+    --------
+    Suppose we wish to minimize the following function.
+
+    >>> def f(x, c=1):
+    ...     return (x - c)**2 + 2
+
+    First, we must find a valid bracket. The function is unimodal,
+    so `bracket_minium` will easily find a bracket.
+
+    >>> from scipy.optimize import elementwise
+    >>> res_bracket = elementwise.bracket_minimum(f, 0)
+    >>> res_bracket.success
+    True
+    >>> res_bracket.bracket
+    (0.0, 0.5, 1.5)
+
+    Indeed, the bracket points are ordered and the function value
+    at the middle bracket point is less than at the surrounding
+    points.
+
+    >>> xl, xm, xr = res_bracket.bracket
+    >>> fl, fm, fr = res_bracket.f_bracket
+    >>> (xl < xm < xr) and (fl > fm <= fr)
+    True
+
+    Once we have a valid bracket, `find_minimum` can be used to provide
+    an estimate of the minimizer.
+
+    >>> res_minimum = elementwise.find_minimum(f, res_bracket.bracket)
+    >>> res_minimum.x
+    1.0000000149011612
+
+    `bracket_minimum` and `find_minimum` accept arrays for most arguments.
+    For instance, to find the minimizers and minima for a few values of the
+    parameter ``c`` at once:
+
+    >>> import numpy as np
+    >>> c = np.asarray([1, 1.5, 2])
+    >>> res_bracket = elementwise.bracket_minimum(f, 0, args=(c,))
+    >>> res_bracket.bracket
+    (array([0. , 0.5, 0.5]), array([0.5, 1.5, 1.5]), array([1.5, 2.5, 2.5]))
+    >>> res_minimum = elementwise.find_minimum(f, res_bracket.bracket, args=(c,))
+    >>> res_minimum.x
+    array([1.00000001, 1.5       , 2.        ])
+    >>> res_minimum.f_x
+    array([2., 2., 2.])
+
+    """  # noqa: E501
+
+    res = _bracket_minimum(f, xm0, xl0=xl0, xr0=xr0, xmin=xmin, xmax=xmax,
+                           factor=factor, args=args, maxiter=maxiter)
+    res.bracket = res.xl, res.xm, res.xr
+    res.f_bracket = res.fl, res.fm, res.fr
+    del res.xl
+    del res.xm
+    del res.xr
+    del res.fl
+    del res.fm
+    del res.fr
+    return res

venv/lib/python3.13/site-packages/scipy/optimize/_hessian_update_strategy.py

@@ -0,0 +1,479 @@
+"""Hessian update strategies for quasi-Newton optimization methods."""
+import numpy as np
+from numpy.linalg import norm
+from scipy.linalg import get_blas_funcs, issymmetric
+from warnings import warn
+
+
+__all__ = ['HessianUpdateStrategy', 'BFGS', 'SR1']
+
+
+class HessianUpdateStrategy:
+    """Interface for implementing Hessian update strategies.
+
+    Many optimization methods make use of Hessian (or inverse Hessian)
+    approximations, such as the quasi-Newton methods BFGS, SR1, L-BFGS.
+    Some of these  approximations, however, do not actually need to store
+    the entire matrix or can compute the internal matrix product with a
+    given vector in a very efficiently manner. This class serves as an
+    abstract interface between the optimization algorithm and the
+    quasi-Newton update strategies, giving freedom of implementation
+    to store and update the internal matrix as efficiently as possible.
+    Different choices of initialization and update procedure will result
+    in different quasi-Newton strategies.
+
+    Four methods should be implemented in derived classes: ``initialize``,
+    ``update``, ``dot`` and ``get_matrix``. The matrix multiplication
+    operator ``@`` is also defined to call the ``dot`` method.
+
+    Notes
+    -----
+    Any instance of a class that implements this interface,
+    can be accepted by the method ``minimize`` and used by
+    the compatible solvers to approximate the Hessian (or
+    inverse Hessian) used by the optimization algorithms.
+    """
+
+    def initialize(self, n, approx_type):
+        """Initialize internal matrix.
+
+        Allocate internal memory for storing and updating
+        the Hessian or its inverse.
+
+        Parameters
+        ----------
+        n : int
+            Problem dimension.
+        approx_type : {'hess', 'inv_hess'}
+            Selects either the Hessian or the inverse Hessian.
+            When set to 'hess' the Hessian will be stored and updated.
+            When set to 'inv_hess' its inverse will be used instead.
+        """
+        raise NotImplementedError("The method ``initialize(n, approx_type)``"
+                                  " is not implemented.")
+
+    def update(self, delta_x, delta_grad):
+        """Update internal matrix.
+
+        Update Hessian matrix or its inverse (depending on how 'approx_type'
+        is defined) using information about the last evaluated points.
+
+        Parameters
+        ----------
+        delta_x : ndarray
+            The difference between two points the gradient
+            function have been evaluated at: ``delta_x = x2 - x1``.
+        delta_grad : ndarray
+            The difference between the gradients:
+            ``delta_grad = grad(x2) - grad(x1)``.
+        """
+        raise NotImplementedError("The method ``update(delta_x, delta_grad)``"
+                                  " is not implemented.")
+
+    def dot(self, p):
+        """Compute the product of the internal matrix with the given vector.
+
+        Parameters
+        ----------
+        p : array_like
+            1-D array representing a vector.
+
+        Returns
+        -------
+        Hp : array
+            1-D represents the result of multiplying the approximation matrix
+            by vector p.
+        """
+        raise NotImplementedError("The method ``dot(p)``"
+                                  " is not implemented.")
+
+    def get_matrix(self):
+        """Return current internal matrix.
+
+        Returns
+        -------
+        H : ndarray, shape (n, n)
+            Dense matrix containing either the Hessian
+            or its inverse (depending on how 'approx_type'
+            is defined).
+        """
+        raise NotImplementedError("The method ``get_matrix(p)``"
+                                  " is not implemented.")
+
+    def __matmul__(self, p):
+        return self.dot(p)
+
+
+class FullHessianUpdateStrategy(HessianUpdateStrategy):
+    """Hessian update strategy with full dimensional internal representation.
+    """
+    _syr = get_blas_funcs('syr', dtype='d')  # Symmetric rank 1 update
+    _syr2 = get_blas_funcs('syr2', dtype='d')  # Symmetric rank 2 update
+    # Symmetric matrix-vector product
+    _symv = get_blas_funcs('symv', dtype='d')
+
+    def __init__(self, init_scale='auto'):
+        self.init_scale = init_scale
+        # Until initialize is called we can't really use the class,
+        # so it makes sense to set everything to None.
+        self.first_iteration = None
+        self.approx_type = None
+        self.B = None
+        self.H = None
+
+    def initialize(self, n, approx_type):
+        """Initialize internal matrix.
+
+        Allocate internal memory for storing and updating
+        the Hessian or its inverse.
+
+        Parameters
+        ----------
+        n : int
+            Problem dimension.
+        approx_type : {'hess', 'inv_hess'}
+            Selects either the Hessian or the inverse Hessian.
+            When set to 'hess' the Hessian will be stored and updated.
+            When set to 'inv_hess' its inverse will be used instead.
+        """
+        self.first_iteration = True
+        self.n = n
+        self.approx_type = approx_type
+        if approx_type not in ('hess', 'inv_hess'):
+            raise ValueError("`approx_type` must be 'hess' or 'inv_hess'.")
+        # Create matrix
+        if self.approx_type == 'hess':
+            self.B = np.eye(n, dtype=float)
+        else:
+            self.H = np.eye(n, dtype=float)
+
+    def _auto_scale(self, delta_x, delta_grad):
+        # Heuristic to scale matrix at first iteration.
+        # Described in Nocedal and Wright "Numerical Optimization"
+        # p.143 formula (6.20).
+        s_norm2 = np.dot(delta_x, delta_x)
+        y_norm2 = np.dot(delta_grad, delta_grad)
+        ys = np.abs(np.dot(delta_grad, delta_x))
+        if ys == 0.0 or y_norm2 == 0 or s_norm2 == 0:
+            return 1
+        if self.approx_type == 'hess':
+            return y_norm2 / ys
+        else:
+            return ys / y_norm2
+
+    def _update_implementation(self, delta_x, delta_grad):
+        raise NotImplementedError("The method ``_update_implementation``"
+                                  " is not implemented.")
+
+    def update(self, delta_x, delta_grad):
+        """Update internal matrix.
+
+        Update Hessian matrix or its inverse (depending on how 'approx_type'
+        is defined) using information about the last evaluated points.
+
+        Parameters
+        ----------
+        delta_x : ndarray
+            The difference between two points the gradient
+            function have been evaluated at: ``delta_x = x2 - x1``.
+        delta_grad : ndarray
+            The difference between the gradients:
+            ``delta_grad = grad(x2) - grad(x1)``.
+        """
+        if np.all(delta_x == 0.0):
+            return
+        if np.all(delta_grad == 0.0):
+            warn('delta_grad == 0.0. Check if the approximated '
+                 'function is linear. If the function is linear '
+                 'better results can be obtained by defining the '
+                 'Hessian as zero instead of using quasi-Newton '
+                 'approximations.',
+                 UserWarning, stacklevel=2)
+            return
+        if self.first_iteration:
+            # Get user specific scale
+            if isinstance(self.init_scale, str) and self.init_scale == "auto":
+                scale = self._auto_scale(delta_x, delta_grad)
+            else:
+                scale = self.init_scale
+
+            # Check for complex: numpy will silently cast a complex array to
+            # a real one but not so for scalar as it raises a TypeError.
+            # Checking here brings a consistent behavior.
+            replace = False
+            if np.size(scale) == 1:
+                # to account for the legacy behavior having the exact same cast
+                scale = float(scale)
+            elif np.iscomplexobj(scale):
+                raise TypeError("init_scale contains complex elements, "
+                                "must be real.")
+            else:  # test explicitly for allowed shapes and values
+                replace = True
+                if self.approx_type == 'hess':
+                    shape = np.shape(self.B)
+                    dtype = self.B.dtype
+                else:
+                    shape = np.shape(self.H)
+                    dtype = self.H.dtype
+                # copy, will replace the original
+                scale = np.array(scale, dtype=dtype, copy=True)
+
+                # it has to match the shape of the matrix for the multiplication,
+                # no implicit broadcasting is allowed
+                if shape != (init_shape := np.shape(scale)):
+                    raise ValueError("If init_scale is an array, it must have the "
+                                     f"dimensions of the hess/inv_hess: {shape}."
+                                     f" Got {init_shape}.")
+                if not issymmetric(scale):
+                    raise ValueError("If init_scale is an array, it must be"
+                                     " symmetric (passing scipy.linalg.issymmetric)"
+                                     " to be an approximation of a hess/inv_hess.")
+
+            # Scale initial matrix with ``scale * np.eye(n)`` or replace
+            # This is not ideal, we could assign the scale directly in
+            # initialize, but we would need to
+            if self.approx_type == 'hess':
+                if replace:
+                    self.B = scale
+                else:
+                    self.B *= scale
+            else:
+                if replace:
+                    self.H = scale
+                else:
+                    self.H *= scale
+            self.first_iteration = False
+        self._update_implementation(delta_x, delta_grad)
+
+    def dot(self, p):
+        """Compute the product of the internal matrix with the given vector.
+
+        Parameters
+        ----------
+        p : array_like
+            1-D array representing a vector.
+
+        Returns
+        -------
+        Hp : array
+            1-D represents the result of multiplying the approximation matrix
+            by vector p.
+        """
+        if self.approx_type == 'hess':
+            return self._symv(1, self.B, p)
+        else:
+            return self._symv(1, self.H, p)
+
+    def get_matrix(self):
+        """Return the current internal matrix.
+
+        Returns
+        -------
+        M : ndarray, shape (n, n)
+            Dense matrix containing either the Hessian or its inverse
+            (depending on how `approx_type` was defined).
+        """
+        if self.approx_type == 'hess':
+            M = np.copy(self.B)
+        else:
+            M = np.copy(self.H)
+        li = np.tril_indices_from(M, k=-1)
+        M[li] = M.T[li]
+        return M
+
+
+class BFGS(FullHessianUpdateStrategy):
+    """Broyden-Fletcher-Goldfarb-Shanno (BFGS) Hessian update strategy.
+
+    Parameters
+    ----------
+    exception_strategy : {'skip_update', 'damp_update'}, optional
+        Define how to proceed when the curvature condition is violated.
+        Set it to 'skip_update' to just skip the update. Or, alternatively,
+        set it to 'damp_update' to interpolate between the actual BFGS
+        result and the unmodified matrix. Both exceptions strategies
+        are explained  in [1]_, p.536-537.
+    min_curvature : float
+        This number, scaled by a normalization factor, defines the
+        minimum curvature ``dot(delta_grad, delta_x)`` allowed to go
+        unaffected by the exception strategy. By default is equal to
+        1e-8 when ``exception_strategy = 'skip_update'`` and equal
+        to 0.2 when ``exception_strategy = 'damp_update'``.
+    init_scale : {float, np.array, 'auto'}
+        This parameter can be used to initialize the Hessian or its
+        inverse. When a float is given, the relevant array is initialized
+        to ``np.eye(n) * init_scale``, where ``n`` is the problem dimension.
+        Alternatively, if a precisely ``(n, n)`` shaped, symmetric array is given,
+        this array will be used. Otherwise an error is generated.
+        Set it to 'auto' in order to use an automatic heuristic for choosing
+        the initial scale. The heuristic is described in [1]_, p.143.
+        The default is 'auto'.
+
+    Notes
+    -----
+    The update is based on the description in [1]_, p.140.
+
+    References
+    ----------
+    .. [1] Nocedal, Jorge, and Stephen J. Wright. "Numerical optimization"
+           Second Edition (2006).
+    """
+
+    def __init__(self, exception_strategy='skip_update', min_curvature=None,
+                 init_scale='auto'):
+        if exception_strategy == 'skip_update':
+            if min_curvature is not None:
+                self.min_curvature = min_curvature
+            else:
+                self.min_curvature = 1e-8
+        elif exception_strategy == 'damp_update':
+            if min_curvature is not None:
+                self.min_curvature = min_curvature
+            else:
+                self.min_curvature = 0.2
+        else:
+            raise ValueError("`exception_strategy` must be 'skip_update' "
+                             "or 'damp_update'.")
+
+        super().__init__(init_scale)
+        self.exception_strategy = exception_strategy
+
+    def _update_inverse_hessian(self, ys, Hy, yHy, s):
+        """Update the inverse Hessian matrix.
+
+        BFGS update using the formula:
+
+            ``H <- H + ((H*y).T*y + s.T*y)/(s.T*y)^2 * (s*s.T)
+                     - 1/(s.T*y) * ((H*y)*s.T + s*(H*y).T)``
+
+        where ``s = delta_x`` and ``y = delta_grad``. This formula is
+        equivalent to (6.17) in [1]_ written in a more efficient way
+        for implementation.
+
+        References
+        ----------
+        .. [1] Nocedal, Jorge, and Stephen J. Wright. "Numerical optimization"
+               Second Edition (2006).
+        """
+        self.H = self._syr2(-1.0 / ys, s, Hy, a=self.H)
+        self.H = self._syr((ys + yHy) / ys ** 2, s, a=self.H)
+
+    def _update_hessian(self, ys, Bs, sBs, y):
+        """Update the Hessian matrix.
+
+        BFGS update using the formula:
+
+            ``B <- B - (B*s)*(B*s).T/s.T*(B*s) + y*y^T/s.T*y``
+
+        where ``s`` is short for ``delta_x`` and ``y`` is short
+        for ``delta_grad``. Formula (6.19) in [1]_.
+
+        References
+        ----------
+        .. [1] Nocedal, Jorge, and Stephen J. Wright. "Numerical optimization"
+               Second Edition (2006).
+        """
+        self.B = self._syr(1.0 / ys, y, a=self.B)
+        self.B = self._syr(-1.0 / sBs, Bs, a=self.B)
+
+    def _update_implementation(self, delta_x, delta_grad):
+        # Auxiliary variables w and z
+        if self.approx_type == 'hess':
+            w = delta_x
+            z = delta_grad
+        else:
+            w = delta_grad
+            z = delta_x
+        # Do some common operations
+        wz = np.dot(w, z)
+        Mw = self @ w
+        wMw = Mw.dot(w)
+        # Guarantee that wMw > 0 by reinitializing matrix.
+        # While this is always true in exact arithmetic,
+        # indefinite matrix may appear due to roundoff errors.
+        if wMw <= 0.0:
+            scale = self._auto_scale(delta_x, delta_grad)
+            # Reinitialize matrix
+            if self.approx_type == 'hess':
+                self.B = scale * np.eye(self.n, dtype=float)
+            else:
+                self.H = scale * np.eye(self.n, dtype=float)
+            # Do common operations for new matrix
+            Mw = self @ w
+            wMw = Mw.dot(w)
+        # Check if curvature condition is violated
+        if wz <= self.min_curvature * wMw:
+            # If the option 'skip_update' is set
+            # we just skip the update when the condition
+            # is violated.
+            if self.exception_strategy == 'skip_update':
+                return
+            # If the option 'damp_update' is set we
+            # interpolate between the actual BFGS
+            # result and the unmodified matrix.
+            elif self.exception_strategy == 'damp_update':
+                update_factor = (1-self.min_curvature) / (1 - wz/wMw)
+                z = update_factor*z + (1-update_factor)*Mw
+                wz = np.dot(w, z)
+        # Update matrix
+        if self.approx_type == 'hess':
+            self._update_hessian(wz, Mw, wMw, z)
+        else:
+            self._update_inverse_hessian(wz, Mw, wMw, z)
+
+
+class SR1(FullHessianUpdateStrategy):
+    """Symmetric-rank-1 Hessian update strategy.
+
+    Parameters
+    ----------
+    min_denominator : float
+        This number, scaled by a normalization factor,
+        defines the minimum denominator magnitude allowed
+        in the update. When the condition is violated we skip
+        the update. By default uses ``1e-8``.
+    init_scale : {float, np.array, 'auto'}, optional
+        This parameter can be used to initialize the Hessian or its
+        inverse. When a float is given, the relevant array is initialized
+        to ``np.eye(n) * init_scale``, where ``n`` is the problem dimension.
+        Alternatively, if a precisely ``(n, n)`` shaped, symmetric array is given,
+        this array will be used. Otherwise an error is generated.
+        Set it to 'auto' in order to use an automatic heuristic for choosing
+        the initial scale. The heuristic is described in [1]_, p.143.
+        The default is 'auto'.
+
+    Notes
+    -----
+    The update is based on the description in [1]_, p.144-146.
+
+    References
+    ----------
+    .. [1] Nocedal, Jorge, and Stephen J. Wright. "Numerical optimization"
+           Second Edition (2006).
+    """
+
+    def __init__(self, min_denominator=1e-8, init_scale='auto'):
+        self.min_denominator = min_denominator
+        super().__init__(init_scale)
+
+    def _update_implementation(self, delta_x, delta_grad):
+        # Auxiliary variables w and z
+        if self.approx_type == 'hess':
+            w = delta_x
+            z = delta_grad
+        else:
+            w = delta_grad
+            z = delta_x
+        # Do some common operations
+        Mw = self @ w
+        z_minus_Mw = z - Mw
+        denominator = np.dot(w, z_minus_Mw)
+        # If the denominator is too small
+        # we just skip the update.
+        if np.abs(denominator) <= self.min_denominator*norm(w)*norm(z_minus_Mw):
+            return
+        # Update matrix
+        if self.approx_type == 'hess':
+            self.B = self._syr(1/denominator, z_minus_Mw, a=self.B)
+        else:
+            self.H = self._syr(1/denominator, z_minus_Mw, a=self.H)

venv/lib/python3.13/site-packages/scipy/optimize/_highspy/_highs_wrapper.py

@@ -0,0 +1,338 @@
+from warnings import warn
+
+import numpy as np
+import scipy.optimize._highspy._core as _h # type: ignore[import-not-found]
+from scipy.optimize._highspy import _highs_options as hopt  # type: ignore[attr-defined]
+from scipy.optimize import OptimizeWarning
+
+
+def _highs_wrapper(c, indptr, indices, data, lhs, rhs, lb, ub, integrality, options):
+    '''Solve linear programs using HiGHS [1]_.
+
+    Assume problems of the form:
+
+        MIN c.T @ x
+        s.t. lhs <= A @ x <= rhs
+             lb <= x <= ub
+
+    Parameters
+    ----------
+    c : 1-D array, (n,)
+        Array of objective value coefficients.
+    astart : 1-D array
+        CSC format index array.
+    aindex : 1-D array
+        CSC format index array.
+    avalue : 1-D array
+        Data array of the matrix.
+    lhs : 1-D array (or None), (m,)
+        Array of left hand side values of the inequality constraints.
+        If ``lhs=None``, then an array of ``-inf`` is assumed.
+    rhs : 1-D array, (m,)
+        Array of right hand side values of the inequality constraints.
+    lb : 1-D array (or None), (n,)
+        Lower bounds on solution variables x.  If ``lb=None``, then an
+        array of all `0` is assumed.
+    ub : 1-D array (or None), (n,)
+        Upper bounds on solution variables x.  If ``ub=None``, then an
+        array of ``inf`` is assumed.
+    options : dict
+        A dictionary of solver options
+
+    Returns
+    -------
+    res : dict
+
+        If model_status is one of kOptimal,
+        kObjectiveBound, kTimeLimit,
+        kIterationLimit:
+
+            - ``status`` : HighsModelStatus
+                Model status code.
+
+            - ``message`` : str
+                Message corresponding to model status code.
+
+            - ``x`` : list
+                Solution variables.
+
+            - ``slack`` : list
+                Slack variables.
+
+            - ``lambda`` : list
+                Lagrange multipliers associated with the constraints
+                Ax = b.
+
+            - ``s`` : list
+                Lagrange multipliers associated with the constraints
+                x >= 0.
+
+            - ``fun``
+                Final objective value.
+
+            - ``simplex_nit`` : int
+                Number of iterations accomplished by the simplex
+                solver.
+
+            - ``ipm_nit`` : int
+                Number of iterations accomplished by the interior-
+                point solver.
+
+        If model_status is not one of the above:
+
+            - ``status`` : HighsModelStatus
+                Model status code.
+
+            - ``message`` : str
+                Message corresponding to model status code.
+
+    Notes
+    -----
+    If ``options['write_solution_to_file']`` is ``True`` but
+    ``options['solution_file']`` is unset or ``''``, then the solution
+    will be printed to ``stdout``.
+
+    If any iteration limit is reached, no solution will be
+    available.
+
+    ``OptimizeWarning`` will be raised if any option value set by
+    the user is found to be incorrect.
+
+    References
+    ----------
+    .. [1] https://highs.dev/
+    .. [2] https://www.maths.ed.ac.uk/hall/HiGHS/HighsOptions.html
+    '''
+    numcol = c.size
+    numrow = rhs.size
+    isMip = integrality is not None and np.sum(integrality) > 0
+
+    # default "null" return values
+    res = {
+        "x": None,
+        "fun": None,
+    }
+
+    # Fill up a HighsLp object
+    lp = _h.HighsLp()
+    lp.num_col_ = numcol
+    lp.num_row_ = numrow
+    lp.a_matrix_.num_col_ = numcol
+    lp.a_matrix_.num_row_ = numrow
+    lp.a_matrix_.format_ = _h.MatrixFormat.kColwise
+    lp.col_cost_ = c
+    lp.col_lower_ = lb
+    lp.col_upper_ = ub
+    lp.row_lower_ = lhs
+    lp.row_upper_ = rhs
+    lp.a_matrix_.start_ = indptr
+    lp.a_matrix_.index_ = indices
+    lp.a_matrix_.value_ = data
+    if integrality.size > 0:
+        lp.integrality_ = [_h.HighsVarType(i) for i in integrality]
+
+    # Make a Highs object and pass it everything
+    highs = _h._Highs()
+    highs_options = _h.HighsOptions()
+    hoptmanager = hopt.HighsOptionsManager()
+    for key, val in options.items():
+        # handle filtering of unsupported and default options
+        if val is None or key in ("sense",):
+            continue
+
+        # ask for the option type
+        opt_type = hoptmanager.get_option_type(key)
+        if -1 == opt_type:
+            warn(
+                f"Unrecognized options detected: {dict({key: val})}",
+                OptimizeWarning,
+                stacklevel=2,
+            )
+            continue
+        else:
+            if key in ("presolve", "parallel"):
+                # handle fake bools (require bool -> str conversions)
+                if isinstance(val, bool):
+                    val = "on" if val else "off"
+                else:
+                    warn(
+                        f'Option f"{key}" is "{val}", but only True or False is '
+                        f"allowed. Using default.",
+                        OptimizeWarning,
+                        stacklevel=2,
+                    )
+                    continue
+            opt_type = _h.HighsOptionType(opt_type)
+            status, msg = check_option(highs, key, val)
+            if opt_type == _h.HighsOptionType.kBool:
+                if not isinstance(val, bool):
+                    warn(
+                        f'Option f"{key}" is "{val}", but only True or False is '
+                        f"allowed. Using default.",
+                        OptimizeWarning,
+                        stacklevel=2,
+                    )
+                    continue
+
+            # warn or set option
+            if status != 0:
+                warn(msg, OptimizeWarning, stacklevel=2)
+            else:
+                setattr(highs_options, key, val)
+
+    opt_status = highs.passOptions(highs_options)
+    if opt_status == _h.HighsStatus.kError:
+        res.update(
+            {
+                "status": highs.getModelStatus(),
+                "message": highs.modelStatusToString(highs.getModelStatus()),
+            }
+        )
+        return res
+
+    init_status = highs.passModel(lp)
+    if init_status == _h.HighsStatus.kError:
+        # if model fails to load, highs.getModelStatus() will be NOT_SET
+        err_model_status = _h.HighsModelStatus.kModelError
+        res.update(
+            {
+                "status": err_model_status,
+                "message": highs.modelStatusToString(err_model_status),
+            }
+        )
+        return res
+
+    # Solve the LP
+    run_status = highs.run()
+    if run_status == _h.HighsStatus.kError:
+        res.update(
+            {
+                "status": highs.getModelStatus(),
+                "message": highs.modelStatusToString(highs.getModelStatus()),
+            }
+        )
+        return res
+
+    # Extract what we need from the solution
+    model_status = highs.getModelStatus()
+
+    # it should always be safe to get the info object
+    info = highs.getInfo()
+
+    # Failure modes:
+    #     LP: if we have anything other than an Optimal status, it
+    #         is unsafe (and unhelpful) to read any results
+    #    MIP: has a non-Optimal status or has timed out/reached max iterations
+    #             1) If not Optimal/TimedOut/MaxIter status, there is no solution
+    #             2) If TimedOut/MaxIter status, there may be a feasible solution.
+    #                if the objective function value is not Infinity, then the
+    #                current solution is feasible and can be returned.  Else, there
+    #                is no solution.
+    mipFailCondition = model_status not in (
+        _h.HighsModelStatus.kOptimal,
+        _h.HighsModelStatus.kTimeLimit,
+        _h.HighsModelStatus.kIterationLimit,
+        _h.HighsModelStatus.kSolutionLimit,
+    ) or (
+        model_status
+        in {
+            _h.HighsModelStatus.kTimeLimit,
+            _h.HighsModelStatus.kIterationLimit,
+            _h.HighsModelStatus.kSolutionLimit,
+        }
+        and (info.objective_function_value == _h.kHighsInf)
+    )
+    lpFailCondition = model_status != _h.HighsModelStatus.kOptimal
+    if (isMip and mipFailCondition) or (not isMip and lpFailCondition):
+        res.update(
+            {
+                "status": model_status,
+                "message": "model_status is "
+                f"{highs.modelStatusToString(model_status)}; "
+                "primal_status is "
+                f"{highs.solutionStatusToString(info.primal_solution_status)}",
+                "simplex_nit": info.simplex_iteration_count,
+                "ipm_nit": info.ipm_iteration_count,
+                "crossover_nit": info.crossover_iteration_count,
+            }
+        )
+        return res
+
+    # Should be safe to read the solution:
+    solution = highs.getSolution()
+    basis = highs.getBasis()
+
+    # Lagrangians for bounds based on column statuses
+    marg_bnds = np.zeros((2, numcol))
+    basis_col_status = basis.col_status
+    solution_col_dual = solution.col_dual
+    for ii in range(numcol):
+        if basis_col_status[ii] == _h.HighsBasisStatus.kLower:
+            marg_bnds[0, ii] = solution_col_dual[ii]
+        elif basis_col_status[ii] == _h.HighsBasisStatus.kUpper:
+            marg_bnds[1, ii] = solution_col_dual[ii]
+
+    res.update(
+        {
+            "status": model_status,
+            "message": highs.modelStatusToString(model_status),
+            # Primal solution
+            "x": np.array(solution.col_value),
+            # Ax + s = b => Ax = b - s
+            # Note: this is for all constraints (A_ub and A_eq)
+            "slack": rhs - solution.row_value,
+            # lambda are the lagrange multipliers associated with Ax=b
+            "lambda": np.array(solution.row_dual),
+            "marg_bnds": marg_bnds,
+            "fun": info.objective_function_value,
+            "simplex_nit": info.simplex_iteration_count,
+            "ipm_nit": info.ipm_iteration_count,
+            "crossover_nit": info.crossover_iteration_count,
+        }
+    )
+
+    if isMip:
+        res.update(
+            {
+                "mip_node_count": info.mip_node_count,
+                "mip_dual_bound": info.mip_dual_bound,
+                "mip_gap": info.mip_gap,
+            }
+        )
+
+    return res
+
+
+def check_option(highs_inst, option, value):
+    status, option_type = highs_inst.getOptionType(option)
+    hoptmanager = hopt.HighsOptionsManager()
+
+    if status != _h.HighsStatus.kOk:
+        return -1, "Invalid option name."
+
+    valid_types = {
+        _h.HighsOptionType.kBool: bool,
+        _h.HighsOptionType.kInt: int,
+        _h.HighsOptionType.kDouble: float,
+        _h.HighsOptionType.kString: str,
+    }
+
+    expected_type = valid_types.get(option_type, None)
+
+    if expected_type is str:
+        if not hoptmanager.check_string_option(option, value):
+            return -1, "Invalid option value."
+    if expected_type is float:
+        if not hoptmanager.check_double_option(option, value):
+            return -1, "Invalid option value."
+    if expected_type is int:
+        if not hoptmanager.check_int_option(option, value):
+            return -1, "Invalid option value."
+
+    if expected_type is None:
+        return 3, "Unknown option type."
+
+    status, current_value = highs_inst.getOptionValue(option)
+    if status != _h.HighsStatus.kOk:
+        return 4, "Failed to validate option value."
+    return 0, "Check option succeeded."

venv/lib/python3.13/site-packages/scipy/optimize/_isotonic.py

@@ -0,0 +1,157 @@
+from typing import TYPE_CHECKING
+
+import numpy as np
+
+from ._optimize import OptimizeResult
+from ._pava_pybind import pava
+
+if TYPE_CHECKING:
+    import numpy.typing as npt
+
+
+__all__ = ["isotonic_regression"]
+
+
+def isotonic_regression(
+    y: "npt.ArrayLike",
+    *,
+    weights: "npt.ArrayLike | None" = None,
+    increasing: bool = True,
+) -> OptimizeResult:
+    r"""Nonparametric isotonic regression.
+
+    A (not strictly) monotonically increasing array `x` with the same length
+    as `y` is calculated by the pool adjacent violators algorithm (PAVA), see
+    [1]_. See the Notes section for more details.
+
+    Parameters
+    ----------
+    y : (N,) array_like
+        Response variable.
+    weights : (N,) array_like or None
+        Case weights.
+    increasing : bool
+        If True, fit monotonic increasing, i.e. isotonic, regression.
+        If False, fit a monotonic decreasing, i.e. antitonic, regression.
+        Default is True.
+
+    Returns
+    -------
+    res : OptimizeResult
+        The optimization result represented as a ``OptimizeResult`` object.
+        Important attributes are:
+
+        - ``x``: The isotonic regression solution, i.e. an increasing (or
+          decreasing) array of the same length than y, with elements in the
+          range from min(y) to max(y).
+        - ``weights`` : Array with the sum of case weights for each block
+          (or pool) B.
+        - ``blocks``: Array of length B+1 with the indices of the start
+          positions of each block (or pool) B. The j-th block is given by
+          ``x[blocks[j]:blocks[j+1]]`` for which all values are the same.
+
+    Notes
+    -----
+    Given data :math:`y` and case weights :math:`w`, the isotonic regression
+    solves the following optimization problem:
+
+    .. math::
+
+        \operatorname{argmin}_{x_i} \sum_i w_i (y_i - x_i)^2 \quad
+        \text{subject to } x_i \leq x_j \text{ whenever } i \leq j \,.
+
+    For every input value :math:`y_i`, it generates a value :math:`x_i` such
+    that :math:`x` is increasing (but not strictly), i.e.
+    :math:`x_i \leq x_{i+1}`. This is accomplished by the PAVA.
+    The solution consists of pools or blocks, i.e. neighboring elements of
+    :math:`x`, e.g. :math:`x_i` and :math:`x_{i+1}`, that all have the same
+    value.
+
+    Most interestingly, the solution stays the same if the squared loss is
+    replaced by the wide class of Bregman functions which are the unique
+    class of strictly consistent scoring functions for the mean, see [2]_
+    and references therein.
+
+    The implemented version of PAVA according to [1]_ has a computational
+    complexity of O(N) with input size N.
+
+    References
+    ----------
+    .. [1] Busing, F. M. T. A. (2022).
+           Monotone Regression: A Simple and Fast O(n) PAVA Implementation.
+           Journal of Statistical Software, Code Snippets, 102(1), 1-25.
+           :doi:`10.18637/jss.v102.c01`
+    .. [2] Jordan, A.I., Mühlemann, A. & Ziegel, J.F.
+           Characterizing the optimal solutions to the isotonic regression
+           problem for identifiable functionals.
+           Ann Inst Stat Math 74, 489-514 (2022).
+           :doi:`10.1007/s10463-021-00808-0`
+
+    Examples
+    --------
+    This example demonstrates that ``isotonic_regression`` really solves a
+    constrained optimization problem.
+
+    >>> import numpy as np
+    >>> from scipy.optimize import isotonic_regression, minimize
+    >>> y = [1.5, 1.0, 4.0, 6.0, 5.7, 5.0, 7.8, 9.0, 7.5, 9.5, 9.0]
+    >>> def objective(yhat, y):
+    ...     return np.sum((yhat - y)**2)
+    >>> def constraint(yhat, y):
+    ...     # This is for a monotonically increasing regression.
+    ...     return np.diff(yhat)
+    >>> result = minimize(objective, x0=y, args=(y,),
+    ...                   constraints=[{'type': 'ineq',
+    ...                                 'fun': lambda x: constraint(x, y)}])
+    >>> result.x
+    array([1.25      , 1.25      , 4.        , 5.56666667, 5.56666667,
+           5.56666667, 7.8       , 8.25      , 8.25      , 9.25      ,
+           9.25      ])
+    >>> result = isotonic_regression(y)
+    >>> result.x
+    array([1.25      , 1.25      , 4.        , 5.56666667, 5.56666667,
+           5.56666667, 7.8       , 8.25      , 8.25      , 9.25      ,
+           9.25      ])
+
+    The big advantage of ``isotonic_regression`` compared to calling
+    ``minimize`` is that it is more user friendly, i.e. one does not need to
+    define objective and constraint functions, and that it is orders of
+    magnitudes faster. On commodity hardware (in 2023), for normal distributed
+    input y of length 1000, the minimizer takes about 4 seconds, while
+    ``isotonic_regression`` takes about 200 microseconds.
+    """
+    yarr = np.atleast_1d(y)  # Check yarr.ndim == 1 is implicit (pybind11) in pava.
+    order = slice(None) if increasing else slice(None, None, -1)
+    x = np.array(yarr[order], order="C", dtype=np.float64, copy=True)
+    if weights is None:
+        wx = np.ones_like(yarr, dtype=np.float64)
+    else:
+        warr = np.atleast_1d(weights)
+
+        if not (yarr.ndim == warr.ndim == 1 and yarr.shape[0] == warr.shape[0]):
+            raise ValueError(
+                "Input arrays y and w must have one dimension of equal length."
+            )
+        if np.any(warr <= 0):
+            raise ValueError("Weights w must be strictly positive.")
+
+        wx = np.array(warr[order], order="C", dtype=np.float64, copy=True)
+    n = x.shape[0]
+    r = np.full(shape=n + 1, fill_value=-1, dtype=np.intp)
+    x, wx, r, b = pava(x, wx, r)
+    # Now that we know the number of blocks b, we only keep the relevant part
+    # of r and wx.
+    # As information: Due to the pava implementation, after the last block
+    # index, there might be smaller numbers appended to r, e.g.
+    # r = [0, 10, 8, 7] which in the end should be r = [0, 10].
+    r = r[:b + 1]  # type: ignore[assignment]
+    wx = wx[:b]
+    if not increasing:
+        x = x[::-1]
+        wx = wx[::-1]
+        r = r[-1] - r[::-1]
+    return OptimizeResult(
+        x=x,
+        weights=wx,
+        blocks=r,
+    )

venv/lib/python3.13/site-packages/scipy/optimize/_lbfgsb_py.py

@@ -0,0 +1,634 @@
+"""
+Functions
+---------
+.. autosummary::
+   :toctree: generated/
+
+    fmin_l_bfgs_b
+
+"""
+
+## License for the Python wrapper
+## ==============================
+
+## Copyright (c) 2004 David M. Cooke <cookedm@physics.mcmaster.ca>
+
+## Permission is hereby granted, free of charge, to any person obtaining a
+## copy of this software and associated documentation files (the "Software"),
+## to deal in the Software without restriction, including without limitation
+## the rights to use, copy, modify, merge, publish, distribute, sublicense,
+## and/or sell copies of the Software, and to permit persons to whom the
+## Software is furnished to do so, subject to the following conditions:
+
+## The above copyright notice and this permission notice shall be included in
+## all copies or substantial portions of the Software.
+
+## THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+## IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+## FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+## AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+## LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+## FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+## DEALINGS IN THE SOFTWARE.
+
+## Modifications by Travis Oliphant and Enthought, Inc. for inclusion in SciPy
+
+import numpy as np
+from numpy import array, asarray, float64, zeros
+from . import _lbfgsb
+from ._optimize import (MemoizeJac, OptimizeResult, _call_callback_maybe_halt,
+                        _wrap_callback, _check_unknown_options,
+                        _prepare_scalar_function)
+from ._constraints import old_bound_to_new
+
+from scipy.sparse.linalg import LinearOperator
+from scipy._lib.deprecation import _NoValue
+import warnings
+
+__all__ = ['fmin_l_bfgs_b', 'LbfgsInvHessProduct']
+
+
+status_messages = {
+    0 : "START",
+    1 : "NEW_X",
+    2 : "RESTART",
+    3 : "FG",
+    4 : "CONVERGENCE",
+    5 : "STOP",
+    6 : "WARNING",
+    7 : "ERROR",
+    8 : "ABNORMAL"
+}
+
+
+task_messages = {
+    0 : "",
+    301 : "",
+    302 : "",
+    401 : "NORM OF PROJECTED GRADIENT <= PGTOL",
+    402 : "RELATIVE REDUCTION OF F <= FACTR*EPSMCH",
+    501 : "CPU EXCEEDING THE TIME LIMIT",
+    502 : "TOTAL NO. OF F,G EVALUATIONS EXCEEDS LIMIT",
+    503 : "PROJECTED GRADIENT IS SUFFICIENTLY SMALL",
+    504 : "TOTAL NO. OF ITERATIONS REACHED LIMIT",
+    505 : "CALLBACK REQUESTED HALT",
+    601 : "ROUNDING ERRORS PREVENT PROGRESS",
+    602 : "STP = STPMAX",
+    603 : "STP = STPMIN",
+    604 : "XTOL TEST SATISFIED",
+    701 : "NO FEASIBLE SOLUTION",
+    702 : "FACTR < 0",
+    703 : "FTOL < 0",
+    704 : "GTOL < 0",
+    705 : "XTOL < 0",
+    706 : "STP < STPMIN",
+    707 : "STP > STPMAX",
+    708 : "STPMIN < 0",
+    709 : "STPMAX < STPMIN",
+    710 : "INITIAL G >= 0",
+    711 : "M <= 0",
+    712 : "N <= 0",
+    713 : "INVALID NBD",
+}
+
+def fmin_l_bfgs_b(func, x0, fprime=None, args=(),
+                  approx_grad=0,
+                  bounds=None, m=10, factr=1e7, pgtol=1e-5,
+                  epsilon=1e-8,
+                  iprint=_NoValue, maxfun=15000, maxiter=15000, disp=_NoValue,
+                  callback=None, maxls=20):
+    """
+    Minimize a function func using the L-BFGS-B algorithm.
+
+    Parameters
+    ----------
+    func : callable f(x,*args)
+        Function to minimize.
+    x0 : ndarray
+        Initial guess.
+    fprime : callable fprime(x,*args), optional
+        The gradient of `func`. If None, then `func` returns the function
+        value and the gradient (``f, g = func(x, *args)``), unless
+        `approx_grad` is True in which case `func` returns only ``f``.
+    args : sequence, optional
+        Arguments to pass to `func` and `fprime`.
+    approx_grad : bool, optional
+        Whether to approximate the gradient numerically (in which case
+        `func` returns only the function value).
+    bounds : list, optional
+        ``(min, max)`` pairs for each element in ``x``, defining
+        the bounds on that parameter. Use None or +-inf for one of ``min`` or
+        ``max`` when there is no bound in that direction.
+    m : int, optional
+        The maximum number of variable metric corrections
+        used to define the limited memory matrix. (The limited memory BFGS
+        method does not store the full hessian but uses this many terms in an
+        approximation to it.)
+    factr : float, optional
+        The iteration stops when
+        ``(f^k - f^{k+1})/max{|f^k|,|f^{k+1}|,1} <= factr * eps``,
+        where ``eps`` is the machine precision, which is automatically
+        generated by the code. Typical values for `factr` are: 1e12 for
+        low accuracy; 1e7 for moderate accuracy; 10.0 for extremely
+        high accuracy. See Notes for relationship to `ftol`, which is exposed
+        (instead of `factr`) by the `scipy.optimize.minimize` interface to
+        L-BFGS-B.
+    pgtol : float, optional
+        The iteration will stop when
+        ``max{|proj g_i | i = 1, ..., n} <= pgtol``
+        where ``proj g_i`` is the i-th component of the projected gradient.
+    epsilon : float, optional
+        Step size used when `approx_grad` is True, for numerically
+        calculating the gradient
+    iprint : int, optional
+        Deprecated option that previously controlled the text printed on the
+        screen during the problem solution. Now the code does not emit any
+        output and this keyword has no function.
+
+        .. deprecated:: 1.15.0
+            This keyword is deprecated and will be removed from SciPy 1.18.0.
+
+    disp : int, optional
+        Deprecated option that previously controlled the text printed on the
+        screen during the problem solution. Now the code does not emit any
+        output and this keyword has no function.
+
+        .. deprecated:: 1.15.0
+            This keyword is deprecated and will be removed from SciPy 1.18.0.
+
+    maxfun : int, optional
+        Maximum number of function evaluations. Note that this function
+        may violate the limit because of evaluating gradients by numerical
+        differentiation.
+    maxiter : int, optional
+        Maximum number of iterations.
+    callback : callable, optional
+        Called after each iteration, as ``callback(xk)``, where ``xk`` is the
+        current parameter vector.
+    maxls : int, optional
+        Maximum number of line search steps (per iteration). Default is 20.
+
+    Returns
+    -------
+    x : array_like
+        Estimated position of the minimum.
+    f : float
+        Value of `func` at the minimum.
+    d : dict
+        Information dictionary.
+
+        * d['warnflag'] is
+
+          - 0 if converged,
+          - 1 if too many function evaluations or too many iterations,
+          - 2 if stopped for another reason, given in d['task']
+
+        * d['grad'] is the gradient at the minimum (should be 0 ish)
+        * d['funcalls'] is the number of function calls made.
+        * d['nit'] is the number of iterations.
+
+    See also
+    --------
+    minimize: Interface to minimization algorithms for multivariate
+        functions. See the 'L-BFGS-B' `method` in particular. Note that the
+        `ftol` option is made available via that interface, while `factr` is
+        provided via this interface, where `factr` is the factor multiplying
+        the default machine floating-point precision to arrive at `ftol`:
+        ``ftol = factr * numpy.finfo(float).eps``.
+
+    Notes
+    -----
+    SciPy uses a C-translated and modified version of the Fortran code,
+    L-BFGS-B v3.0 (released April 25, 2011, BSD-3 licensed). Original Fortran
+    version was written by Ciyou Zhu, Richard Byrd, Jorge Nocedal and,
+    Jose Luis Morales.
+
+    References
+    ----------
+    * R. H. Byrd, P. Lu and J. Nocedal. A Limited Memory Algorithm for Bound
+      Constrained Optimization, (1995), SIAM Journal on Scientific and
+      Statistical Computing, 16, 5, pp. 1190-1208.
+    * C. Zhu, R. H. Byrd and J. Nocedal. L-BFGS-B: Algorithm 778: L-BFGS-B,
+      FORTRAN routines for large scale bound constrained optimization (1997),
+      ACM Transactions on Mathematical Software, 23, 4, pp. 550 - 560.
+    * J.L. Morales and J. Nocedal. L-BFGS-B: Remark on Algorithm 778: L-BFGS-B,
+      FORTRAN routines for large scale bound constrained optimization (2011),
+      ACM Transactions on Mathematical Software, 38, 1.
+
+    Examples
+    --------
+    Solve a linear regression problem via `fmin_l_bfgs_b`. To do this, first we
+    define an objective function ``f(m, b) = (y - y_model)**2``, where `y`
+    describes the observations and `y_model` the prediction of the linear model
+    as ``y_model = m*x + b``. The bounds for the parameters, ``m`` and ``b``,
+    are arbitrarily chosen as ``(0,5)`` and ``(5,10)`` for this example.
+
+    >>> import numpy as np
+    >>> from scipy.optimize import fmin_l_bfgs_b
+    >>> X = np.arange(0, 10, 1)
+    >>> M = 2
+    >>> B = 3
+    >>> Y = M * X + B
+    >>> def func(parameters, *args):
+    ...     x = args[0]
+    ...     y = args[1]
+    ...     m, b = parameters
+    ...     y_model = m*x + b
+    ...     error = sum(np.power((y - y_model), 2))
+    ...     return error
+
+    >>> initial_values = np.array([0.0, 1.0])
+
+    >>> x_opt, f_opt, info = fmin_l_bfgs_b(func, x0=initial_values, args=(X, Y),
+    ...                                    approx_grad=True)
+    >>> x_opt, f_opt
+    array([1.99999999, 3.00000006]), 1.7746231151323805e-14  # may vary
+
+    The optimized parameters in ``x_opt`` agree with the ground truth parameters
+    ``m`` and ``b``. Next, let us perform a bound constrained optimization using
+    the `bounds` parameter.
+
+    >>> bounds = [(0, 5), (5, 10)]
+    >>> x_opt, f_op, info = fmin_l_bfgs_b(func, x0=initial_values, args=(X, Y),
+    ...                                   approx_grad=True, bounds=bounds)
+    >>> x_opt, f_opt
+    array([1.65990508, 5.31649385]), 15.721334516453945  # may vary
+    """
+    # handle fprime/approx_grad
+    if approx_grad:
+        fun = func
+        jac = None
+    elif fprime is None:
+        fun = MemoizeJac(func)
+        jac = fun.derivative
+    else:
+        fun = func
+        jac = fprime
+
+    # build options
+    callback = _wrap_callback(callback)
+    opts = {'disp': disp,
+            'iprint': iprint,
+            'maxcor': m,
+            'ftol': factr * np.finfo(float).eps,
+            'gtol': pgtol,
+            'eps': epsilon,
+            'maxfun': maxfun,
+            'maxiter': maxiter,
+            'callback': callback,
+            'maxls': maxls}
+
+    res = _minimize_lbfgsb(fun, x0, args=args, jac=jac, bounds=bounds,
+                           **opts)
+    d = {'grad': res['jac'],
+         'task': res['message'],
+         'funcalls': res['nfev'],
+         'nit': res['nit'],
+         'warnflag': res['status']}
+    f = res['fun']
+    x = res['x']
+
+    return x, f, d
+
+
+def _minimize_lbfgsb(fun, x0, args=(), jac=None, bounds=None,
+                     disp=_NoValue, maxcor=10, ftol=2.2204460492503131e-09,
+                     gtol=1e-5, eps=1e-8, maxfun=15000, maxiter=15000,
+                     iprint=_NoValue, callback=None, maxls=20,
+                     finite_diff_rel_step=None, workers=None,
+                     **unknown_options):
+    """
+    Minimize a scalar function of one or more variables using the L-BFGS-B
+    algorithm.
+
+    Options
+    -------
+    disp : None or int
+        Deprecated option that previously controlled the text printed on the
+        screen during the problem solution. Now the code does not emit any
+        output and this keyword has no function.
+
+        .. deprecated:: 1.15.0
+            This keyword is deprecated and will be removed from SciPy 1.18.0.
+
+    maxcor : int
+        The maximum number of variable metric corrections used to
+        define the limited memory matrix. (The limited memory BFGS
+        method does not store the full hessian but uses this many terms
+        in an approximation to it.)
+    ftol : float
+        The iteration stops when ``(f^k -
+        f^{k+1})/max{|f^k|,|f^{k+1}|,1} <= ftol``.
+    gtol : float
+        The iteration will stop when ``max{|proj g_i | i = 1, ..., n}
+        <= gtol`` where ``proj g_i`` is the i-th component of the
+        projected gradient.
+    eps : float or ndarray
+        If `jac is None` the absolute step size used for numerical
+        approximation of the jacobian via forward differences.
+    maxfun : int
+        Maximum number of function evaluations before minimization terminates.
+        Note that this function may violate the limit if the gradients
+        are evaluated by numerical differentiation.
+    maxiter : int
+        Maximum number of algorithm iterations.
+    iprint : int, optional
+        Deprecated option that previously controlled the text printed on the
+        screen during the problem solution. Now the code does not emit any
+        output and this keyword has no function.
+
+        .. deprecated:: 1.15.0
+            This keyword is deprecated and will be removed from SciPy 1.18.0.
+
+    maxls : int, optional
+        Maximum number of line search steps (per iteration). Default is 20.
+    finite_diff_rel_step : None or array_like, optional
+        If ``jac in ['2-point', '3-point', 'cs']`` the relative step size to
+        use for numerical approximation of the jacobian. The absolute step
+        size is computed as ``h = rel_step * sign(x) * max(1, abs(x))``,
+        possibly adjusted to fit into the bounds. For ``method='3-point'``
+        the sign of `h` is ignored. If None (default) then step is selected
+        automatically.
+    workers : int, map-like callable, optional
+        A map-like callable, such as `multiprocessing.Pool.map` for evaluating
+        any numerical differentiation in parallel.
+        This evaluation is carried out as ``workers(fun, iterable)``.
+
+        .. versionadded:: 1.16.0
+
+    Notes
+    -----
+    The option `ftol` is exposed via the `scipy.optimize.minimize` interface,
+    but calling `scipy.optimize.fmin_l_bfgs_b` directly exposes `factr`. The
+    relationship between the two is ``ftol = factr * numpy.finfo(float).eps``.
+    I.e., `factr` multiplies the default machine floating-point precision to
+    arrive at `ftol`.
+    If the minimization is slow to converge the optimizer may halt if the
+    total number of function evaluations exceeds `maxfun`, or the number of
+    algorithm iterations has reached `maxiter` (whichever comes first). If
+    this is the case then ``result.success=False``, and an appropriate
+    error message is contained in ``result.message``.
+
+    """
+    _check_unknown_options(unknown_options)
+    m = maxcor
+    pgtol = gtol
+    factr = ftol / np.finfo(float).eps
+
+    x0 = asarray(x0).ravel()
+    n, = x0.shape
+    if disp is not _NoValue:
+        warnings.warn("scipy.optimize: The `disp` and `iprint` options of the "
+                      "L-BFGS-B solver are deprecated and will be removed in "
+                      "SciPy 1.18.0.",
+                      DeprecationWarning, stacklevel=3)
+
+    if iprint is not _NoValue:
+        warnings.warn("scipy.optimize: The `disp` and `iprint` options of the "
+                      "L-BFGS-B solver are deprecated and will be removed in "
+                      "SciPy 1.18.0.",
+                      DeprecationWarning, stacklevel=3)
+
+    # historically old-style bounds were/are expected by lbfgsb.
+    # That's still the case but we'll deal with new-style from here on,
+    # it's easier
+    if bounds is None:
+        pass
+    elif len(bounds) != n:
+        raise ValueError('length of x0 != length of bounds')
+    else:
+        bounds = np.array(old_bound_to_new(bounds))
+
+        # check bounds
+        if (bounds[0] > bounds[1]).any():
+            raise ValueError(
+                "LBFGSB - one of the lower bounds is greater than an upper bound."
+            )
+
+        # initial vector must lie within the bounds. Otherwise ScalarFunction and
+        # approx_derivative will cause problems
+        x0 = np.clip(x0, bounds[0], bounds[1])
+
+    # _prepare_scalar_function can use bounds=None to represent no bounds
+    sf = _prepare_scalar_function(fun, x0, jac=jac, args=args, epsilon=eps,
+                                  bounds=bounds,
+                                  finite_diff_rel_step=finite_diff_rel_step,
+                                  workers=workers)
+
+    func_and_grad = sf.fun_and_grad
+
+    nbd = zeros(n, np.int32)
+    low_bnd = zeros(n, float64)
+    upper_bnd = zeros(n, float64)
+    bounds_map = {(-np.inf, np.inf): 0,
+                  (1, np.inf): 1,
+                  (1, 1): 2,
+                  (-np.inf, 1): 3}
+
+    if bounds is not None:
+        for i in range(0, n):
+            L, U = bounds[0, i], bounds[1, i]
+            if not np.isinf(L):
+                low_bnd[i] = L
+                L = 1
+            if not np.isinf(U):
+                upper_bnd[i] = U
+                U = 1
+            nbd[i] = bounds_map[L, U]
+
+    if not maxls > 0:
+        raise ValueError('maxls must be positive.')
+
+    x = array(x0, dtype=np.float64)
+    f = array(0.0, dtype=np.int32)
+    g = zeros((n,), dtype=np.int32)
+    wa = zeros(2*m*n + 5*n + 11*m*m + 8*m, float64)
+    iwa = zeros(3*n, dtype=np.int32)
+    task = zeros(2, dtype=np.int32)
+    ln_task = zeros(2, dtype=np.int32)
+    lsave = zeros(4, dtype=np.int32)
+    isave = zeros(44, dtype=np.int32)
+    dsave = zeros(29, dtype=float64)
+
+    n_iterations = 0
+
+    while True:
+        # g may become float32 if a user provides a function that calculates
+        # the Jacobian in float32 (see gh-18730). The underlying code expects
+        # float64, so upcast it
+        g = g.astype(np.float64)
+        # x, f, g, wa, iwa, task, csave, lsave, isave, dsave = \
+        _lbfgsb.setulb(m, x, low_bnd, upper_bnd, nbd, f, g, factr, pgtol, wa,
+                       iwa, task, lsave, isave, dsave, maxls, ln_task)
+
+        if task[0] == 3:
+            # The minimization routine wants f and g at the current x.
+            # Note that interruptions due to maxfun are postponed
+            # until the completion of the current minimization iteration.
+            # Overwrite f and g:
+            f, g = func_and_grad(x)
+        elif task[0] == 1:
+            # new iteration
+            n_iterations += 1
+
+            intermediate_result = OptimizeResult(x=x, fun=f)
+            if _call_callback_maybe_halt(callback, intermediate_result):
+                task[0] = 5
+                task[1] = 505
+            if n_iterations >= maxiter:
+                task[0] = 5
+                task[1] = 504
+            elif sf.nfev > maxfun:
+                task[0] = 5
+                task[1] = 502
+        else:
+            break
+
+    if task[0] == 4:
+        warnflag = 0
+    elif sf.nfev > maxfun or n_iterations >= maxiter:
+        warnflag = 1
+    else:
+        warnflag = 2
+
+    # These two portions of the workspace are described in the mainlb
+    # function docstring in "__lbfgsb.c", ws and wy arguments.
+    s = wa[0: m*n].reshape(m, n)
+    y = wa[m*n: 2*m*n].reshape(m, n)
+
+    # isave(31) = the total number of BFGS updates prior the current iteration.
+    n_bfgs_updates = isave[30]
+
+    n_corrs = min(n_bfgs_updates, maxcor)
+    hess_inv = LbfgsInvHessProduct(s[:n_corrs], y[:n_corrs])
+
+    msg = status_messages[task[0]] + ": " + task_messages[task[1]]
+
+    return OptimizeResult(fun=f, jac=g, nfev=sf.nfev,
+                          njev=sf.ngev,
+                          nit=n_iterations, status=warnflag, message=msg,
+                          x=x, success=(warnflag == 0), hess_inv=hess_inv)
+
+
+class LbfgsInvHessProduct(LinearOperator):
+    """Linear operator for the L-BFGS approximate inverse Hessian.
+
+    This operator computes the product of a vector with the approximate inverse
+    of the Hessian of the objective function, using the L-BFGS limited
+    memory approximation to the inverse Hessian, accumulated during the
+    optimization.
+
+    Objects of this class implement the ``scipy.sparse.linalg.LinearOperator``
+    interface.
+
+    Parameters
+    ----------
+    sk : array_like, shape=(n_corr, n)
+        Array of `n_corr` most recent updates to the solution vector.
+        (See [1]).
+    yk : array_like, shape=(n_corr, n)
+        Array of `n_corr` most recent updates to the gradient. (See [1]).
+
+    References
+    ----------
+    .. [1] Nocedal, Jorge. "Updating quasi-Newton matrices with limited
+       storage." Mathematics of computation 35.151 (1980): 773-782.
+
+    """
+
+    def __init__(self, sk, yk):
+        """Construct the operator."""
+        if sk.shape != yk.shape or sk.ndim != 2:
+            raise ValueError('sk and yk must have matching shape, (n_corrs, n)')
+        n_corrs, n = sk.shape
+
+        super().__init__(dtype=np.float64, shape=(n, n))
+
+        self.sk = sk
+        self.yk = yk
+        self.n_corrs = n_corrs
+        self.rho = 1 / np.einsum('ij,ij->i', sk, yk)
+
+    def _matvec(self, x):
+        """Efficient matrix-vector multiply with the BFGS matrices.
+
+        This calculation is described in Section (4) of [1].
+
+        Parameters
+        ----------
+        x : ndarray
+            An array with shape (n,) or (n,1).
+
+        Returns
+        -------
+        y : ndarray
+            The matrix-vector product
+
+        """
+        s, y, n_corrs, rho = self.sk, self.yk, self.n_corrs, self.rho
+        q = np.array(x, dtype=self.dtype, copy=True)
+        if q.ndim == 2 and q.shape[1] == 1:
+            q = q.reshape(-1)
+
+        alpha = np.empty(n_corrs)
+
+        for i in range(n_corrs-1, -1, -1):
+            alpha[i] = rho[i] * np.dot(s[i], q)
+            q = q - alpha[i]*y[i]
+
+        r = q
+        for i in range(n_corrs):
+            beta = rho[i] * np.dot(y[i], r)
+            r = r + s[i] * (alpha[i] - beta)
+
+        return r
+
+    def _matmat(self, X):
+        """Efficient matrix-matrix multiply with the BFGS matrices.
+
+        This calculation is described in Section (4) of [1].
+
+        Parameters
+        ----------
+        X : ndarray
+            An array with shape (n,m)
+
+        Returns
+        -------
+        Y : ndarray
+            The matrix-matrix product
+
+        Notes
+        -----
+        This implementation is written starting from _matvec and broadcasting
+        all expressions along the second axis of X.
+
+        """
+        s, y, n_corrs, rho = self.sk, self.yk, self.n_corrs, self.rho
+        Q = np.array(X, dtype=self.dtype, copy=True)
+
+        alpha = np.empty((n_corrs, Q.shape[1]))
+
+        for i in range(n_corrs-1, -1, -1):
+            alpha[i] = rho[i] * np.dot(s[i], Q)
+            Q -= alpha[i]*y[i][:, np.newaxis]
+
+        R = Q
+        for i in range(n_corrs):
+            beta = rho[i] * np.dot(y[i], R)
+            R += s[i][:, np.newaxis] * (alpha[i] - beta)
+
+        return R
+
+    def todense(self):
+        """Return a dense array representation of this operator.
+
+        Returns
+        -------
+        arr : ndarray, shape=(n, n)
+            An array with the same shape and containing
+            the same data represented by this `LinearOperator`.
+
+        """
+        I_arr = np.eye(*self.shape, dtype=self.dtype)
+        return self._matmat(I_arr)

venv/lib/python3.13/site-packages/scipy/optimize/_linesearch.py

@@ -0,0 +1,896 @@
+"""
+Functions
+---------
+.. autosummary::
+   :toctree: generated/
+
+    line_search_armijo
+    line_search_wolfe1
+    line_search_wolfe2
+    scalar_search_wolfe1
+    scalar_search_wolfe2
+
+"""
+from warnings import warn
+
+from ._dcsrch import DCSRCH
+import numpy as np
+
+__all__ = ['LineSearchWarning', 'line_search_wolfe1', 'line_search_wolfe2',
+           'scalar_search_wolfe1', 'scalar_search_wolfe2',
+           'line_search_armijo']
+
+class LineSearchWarning(RuntimeWarning):
+    pass
+
+
+def _check_c1_c2(c1, c2):
+    if not (0 < c1 < c2 < 1):
+        raise ValueError("'c1' and 'c2' do not satisfy"
+                         "'0 < c1 < c2 < 1'.")
+
+
+#------------------------------------------------------------------------------
+# Minpack's Wolfe line and scalar searches
+#------------------------------------------------------------------------------
+
+def line_search_wolfe1(f, fprime, xk, pk, gfk=None,
+                       old_fval=None, old_old_fval=None,
+                       args=(), c1=1e-4, c2=0.9, amax=50, amin=1e-8,
+                       xtol=1e-14):
+    """
+    As `scalar_search_wolfe1` but do a line search to direction `pk`
+
+    Parameters
+    ----------
+    f : callable
+        Function `f(x)`
+    fprime : callable
+        Gradient of `f`
+    xk : array_like
+        Current point
+    pk : array_like
+        Search direction
+    gfk : array_like, optional
+        Gradient of `f` at point `xk`
+    old_fval : float, optional
+        Value of `f` at point `xk`
+    old_old_fval : float, optional
+        Value of `f` at point preceding `xk`
+
+    The rest of the parameters are the same as for `scalar_search_wolfe1`.
+
+    Returns
+    -------
+    stp, f_count, g_count, fval, old_fval
+        As in `line_search_wolfe1`
+    gval : array
+        Gradient of `f` at the final point
+
+    Notes
+    -----
+    Parameters `c1` and `c2` must satisfy ``0 < c1 < c2 < 1``.
+
+    """
+    if gfk is None:
+        gfk = fprime(xk, *args)
+
+    gval = [gfk]
+    gc = [0]
+    fc = [0]
+
+    def phi(s):
+        fc[0] += 1
+        return f(xk + s*pk, *args)
+
+    def derphi(s):
+        gval[0] = fprime(xk + s*pk, *args)
+        gc[0] += 1
+        return np.dot(gval[0], pk)
+
+    derphi0 = np.dot(gfk, pk)
+
+    stp, fval, old_fval = scalar_search_wolfe1(
+            phi, derphi, old_fval, old_old_fval, derphi0,
+            c1=c1, c2=c2, amax=amax, amin=amin, xtol=xtol)
+
+    return stp, fc[0], gc[0], fval, old_fval, gval[0]
+
+
+def scalar_search_wolfe1(phi, derphi, phi0=None, old_phi0=None, derphi0=None,
+                         c1=1e-4, c2=0.9,
+                         amax=50, amin=1e-8, xtol=1e-14):
+    """
+    Scalar function search for alpha that satisfies strong Wolfe conditions
+
+    alpha > 0 is assumed to be a descent direction.
+
+    Parameters
+    ----------
+    phi : callable phi(alpha)
+        Function at point `alpha`
+    derphi : callable phi'(alpha)
+        Objective function derivative. Returns a scalar.
+    phi0 : float, optional
+        Value of phi at 0
+    old_phi0 : float, optional
+        Value of phi at previous point
+    derphi0 : float, optional
+        Value derphi at 0
+    c1 : float, optional
+        Parameter for Armijo condition rule.
+    c2 : float, optional
+        Parameter for curvature condition rule.
+    amax, amin : float, optional
+        Maximum and minimum step size
+    xtol : float, optional
+        Relative tolerance for an acceptable step.
+
+    Returns
+    -------
+    alpha : float
+        Step size, or None if no suitable step was found
+    phi : float
+        Value of `phi` at the new point `alpha`
+    phi0 : float
+        Value of `phi` at `alpha=0`
+
+    Notes
+    -----
+    Uses routine DCSRCH from MINPACK.
+    
+    Parameters `c1` and `c2` must satisfy ``0 < c1 < c2 < 1`` as described in [1]_.
+
+    References
+    ----------
+    
+    .. [1] Nocedal, J., & Wright, S. J. (2006). Numerical optimization.
+       In Springer Series in Operations Research and Financial Engineering.
+       (Springer Series in Operations Research and Financial Engineering).
+       Springer Nature.
+
+    """
+    _check_c1_c2(c1, c2)
+
+    if phi0 is None:
+        phi0 = phi(0.)
+    if derphi0 is None:
+        derphi0 = derphi(0.)
+
+    if old_phi0 is not None and derphi0 != 0:
+        alpha1 = min(1.0, 1.01*2*(phi0 - old_phi0)/derphi0)
+        if alpha1 < 0:
+            alpha1 = 1.0
+    else:
+        alpha1 = 1.0
+
+    maxiter = 100
+
+    dcsrch = DCSRCH(phi, derphi, c1, c2, xtol, amin, amax)
+    stp, phi1, phi0, task = dcsrch(
+        alpha1, phi0=phi0, derphi0=derphi0, maxiter=maxiter
+    )
+
+    return stp, phi1, phi0
+
+
+line_search = line_search_wolfe1
+
+
+#------------------------------------------------------------------------------
+# Pure-Python Wolfe line and scalar searches
+#------------------------------------------------------------------------------
+
+# Note: `line_search_wolfe2` is the public `scipy.optimize.line_search`
+
+def line_search_wolfe2(f, myfprime, xk, pk, gfk=None, old_fval=None,
+                       old_old_fval=None, args=(), c1=1e-4, c2=0.9, amax=None,
+                       extra_condition=None, maxiter=10):
+    """Find alpha that satisfies strong Wolfe conditions.
+
+    Parameters
+    ----------
+    f : callable f(x,*args)
+        Objective function.
+    myfprime : callable f'(x,*args)
+        Objective function gradient.
+    xk : ndarray
+        Starting point.
+    pk : ndarray
+        Search direction. The search direction must be a descent direction
+        for the algorithm to converge.
+    gfk : ndarray, optional
+        Gradient value for x=xk (xk being the current parameter
+        estimate). Will be recomputed if omitted.
+    old_fval : float, optional
+        Function value for x=xk. Will be recomputed if omitted.
+    old_old_fval : float, optional
+        Function value for the point preceding x=xk.
+    args : tuple, optional
+        Additional arguments passed to objective function.
+    c1 : float, optional
+        Parameter for Armijo condition rule.
+    c2 : float, optional
+        Parameter for curvature condition rule.
+    amax : float, optional
+        Maximum step size
+    extra_condition : callable, optional
+        A callable of the form ``extra_condition(alpha, x, f, g)``
+        returning a boolean. Arguments are the proposed step ``alpha``
+        and the corresponding ``x``, ``f`` and ``g`` values. The line search
+        accepts the value of ``alpha`` only if this
+        callable returns ``True``. If the callable returns ``False``
+        for the step length, the algorithm will continue with
+        new iterates. The callable is only called for iterates
+        satisfying the strong Wolfe conditions.
+    maxiter : int, optional
+        Maximum number of iterations to perform.
+
+    Returns
+    -------
+    alpha : float or None
+        Alpha for which ``x_new = x0 + alpha * pk``,
+        or None if the line search algorithm did not converge.
+    fc : int
+        Number of function evaluations made.
+    gc : int
+        Number of gradient evaluations made.
+    new_fval : float or None
+        New function value ``f(x_new)=f(x0+alpha*pk)``,
+        or None if the line search algorithm did not converge.
+    old_fval : float
+        Old function value ``f(x0)``.
+    new_slope : float or None
+        The local slope along the search direction at the
+        new value ``<myfprime(x_new), pk>``,
+        or None if the line search algorithm did not converge.
+
+
+    Notes
+    -----
+    Uses the line search algorithm to enforce strong Wolfe
+    conditions. See Wright and Nocedal, 'Numerical Optimization',
+    1999, pp. 59-61.
+
+    The search direction `pk` must be a descent direction (e.g.
+    ``-myfprime(xk)``) to find a step length that satisfies the strong Wolfe
+    conditions. If the search direction is not a descent direction (e.g.
+    ``myfprime(xk)``), then `alpha`, `new_fval`, and `new_slope` will be None.
+
+    Examples
+    --------
+    >>> import numpy as np
+    >>> from scipy.optimize import line_search
+
+    A objective function and its gradient are defined.
+
+    >>> def obj_func(x):
+    ...     return (x[0])**2+(x[1])**2
+    >>> def obj_grad(x):
+    ...     return [2*x[0], 2*x[1]]
+
+    We can find alpha that satisfies strong Wolfe conditions.
+
+    >>> start_point = np.array([1.8, 1.7])
+    >>> search_gradient = np.array([-1.0, -1.0])
+    >>> line_search(obj_func, obj_grad, start_point, search_gradient)
+    (1.0, 2, 1, 1.1300000000000001, 6.13, [1.6, 1.4])
+
+    """
+    fc = [0]
+    gc = [0]
+    gval = [None]
+    gval_alpha = [None]
+
+    def phi(alpha):
+        fc[0] += 1
+        return f(xk + alpha * pk, *args)
+
+    fprime = myfprime
+
+    def derphi(alpha):
+        gc[0] += 1
+        gval[0] = fprime(xk + alpha * pk, *args)  # store for later use
+        gval_alpha[0] = alpha
+        return np.dot(gval[0], pk)
+
+    if gfk is None:
+        gfk = fprime(xk, *args)
+    derphi0 = np.dot(gfk, pk)
+
+    if extra_condition is not None:
+        # Add the current gradient as argument, to avoid needless
+        # re-evaluation
+        def extra_condition2(alpha, phi):
+            if gval_alpha[0] != alpha:
+                derphi(alpha)
+            x = xk + alpha * pk
+            return extra_condition(alpha, x, phi, gval[0])
+    else:
+        extra_condition2 = None
+
+    alpha_star, phi_star, old_fval, derphi_star = scalar_search_wolfe2(
+            phi, derphi, old_fval, old_old_fval, derphi0, c1, c2, amax,
+            extra_condition2, maxiter=maxiter)
+
+    if derphi_star is None:
+        warn('The line search algorithm did not converge',
+             LineSearchWarning, stacklevel=2)
+    else:
+        # derphi_star is a number (derphi) -- so use the most recently
+        # calculated gradient used in computing it derphi = gfk*pk
+        # this is the gradient at the next step no need to compute it
+        # again in the outer loop.
+        derphi_star = gval[0]
+
+    return alpha_star, fc[0], gc[0], phi_star, old_fval, derphi_star
+
+
+def scalar_search_wolfe2(phi, derphi, phi0=None,
+                         old_phi0=None, derphi0=None,
+                         c1=1e-4, c2=0.9, amax=None,
+                         extra_condition=None, maxiter=10):
+    """Find alpha that satisfies strong Wolfe conditions.
+
+    alpha > 0 is assumed to be a descent direction.
+
+    Parameters
+    ----------
+    phi : callable phi(alpha)
+        Objective scalar function.
+    derphi : callable phi'(alpha)
+        Objective function derivative. Returns a scalar.
+    phi0 : float, optional
+        Value of phi at 0.
+    old_phi0 : float, optional
+        Value of phi at previous point.
+    derphi0 : float, optional
+        Value of derphi at 0
+    c1 : float, optional
+        Parameter for Armijo condition rule.
+    c2 : float, optional
+        Parameter for curvature condition rule.
+    amax : float, optional
+        Maximum step size.
+    extra_condition : callable, optional
+        A callable of the form ``extra_condition(alpha, phi_value)``
+        returning a boolean. The line search accepts the value
+        of ``alpha`` only if this callable returns ``True``.
+        If the callable returns ``False`` for the step length,
+        the algorithm will continue with new iterates.
+        The callable is only called for iterates satisfying
+        the strong Wolfe conditions.
+    maxiter : int, optional
+        Maximum number of iterations to perform.
+
+    Returns
+    -------
+    alpha_star : float or None
+        Best alpha, or None if the line search algorithm did not converge.
+    phi_star : float
+        phi at alpha_star.
+    phi0 : float
+        phi at 0.
+    derphi_star : float or None
+        derphi at alpha_star, or None if the line search algorithm
+        did not converge.
+
+    Notes
+    -----
+    Uses the line search algorithm to enforce strong Wolfe
+    conditions. See Wright and Nocedal, 'Numerical Optimization',
+    1999, pp. 59-61.
+
+    """
+    _check_c1_c2(c1, c2)
+
+    if phi0 is None:
+        phi0 = phi(0.)
+
+    if derphi0 is None:
+        derphi0 = derphi(0.)
+
+    alpha0 = 0
+    if old_phi0 is not None and derphi0 != 0:
+        alpha1 = min(1.0, 1.01*2*(phi0 - old_phi0)/derphi0)
+    else:
+        alpha1 = 1.0
+
+    if alpha1 < 0:
+        alpha1 = 1.0
+
+    if amax is not None:
+        alpha1 = min(alpha1, amax)
+
+    phi_a1 = phi(alpha1)
+    #derphi_a1 = derphi(alpha1) evaluated below
+
+    phi_a0 = phi0
+    derphi_a0 = derphi0
+
+    if extra_condition is None:
+        def extra_condition(alpha, phi):
+            return True
+
+    for i in range(maxiter):
+        if alpha1 == 0 or (amax is not None and alpha0 > amax):
+            # alpha1 == 0: This shouldn't happen. Perhaps the increment has
+            # slipped below machine precision?
+            alpha_star = None
+            phi_star = phi0
+            phi0 = old_phi0
+            derphi_star = None
+
+            if alpha1 == 0:
+                msg = 'Rounding errors prevent the line search from converging'
+            else:
+                msg = "The line search algorithm could not find a solution " + \
+                      f"less than or equal to amax: {amax}"
+
+            warn(msg, LineSearchWarning, stacklevel=2)
+            break
+
+        not_first_iteration = i > 0
+        if (phi_a1 > phi0 + c1 * alpha1 * derphi0) or \
+           ((phi_a1 >= phi_a0) and not_first_iteration):
+            alpha_star, phi_star, derphi_star = \
+                        _zoom(alpha0, alpha1, phi_a0,
+                              phi_a1, derphi_a0, phi, derphi,
+                              phi0, derphi0, c1, c2, extra_condition)
+            break
+
+        derphi_a1 = derphi(alpha1)
+        if (abs(derphi_a1) <= -c2*derphi0):
+            if extra_condition(alpha1, phi_a1):
+                alpha_star = alpha1
+                phi_star = phi_a1
+                derphi_star = derphi_a1
+                break
+
+        if (derphi_a1 >= 0):
+            alpha_star, phi_star, derphi_star = \
+                        _zoom(alpha1, alpha0, phi_a1,
+                              phi_a0, derphi_a1, phi, derphi,
+                              phi0, derphi0, c1, c2, extra_condition)
+            break
+
+        alpha2 = 2 * alpha1  # increase by factor of two on each iteration
+        if amax is not None:
+            alpha2 = min(alpha2, amax)
+        alpha0 = alpha1
+        alpha1 = alpha2
+        phi_a0 = phi_a1
+        phi_a1 = phi(alpha1)
+        derphi_a0 = derphi_a1
+
+    else:
+        # stopping test maxiter reached
+        alpha_star = alpha1
+        phi_star = phi_a1
+        derphi_star = None
+        warn('The line search algorithm did not converge',
+             LineSearchWarning, stacklevel=2)
+
+    return alpha_star, phi_star, phi0, derphi_star
+
+
+def _cubicmin(a, fa, fpa, b, fb, c, fc):
+    """
+    Finds the minimizer for a cubic polynomial that goes through the
+    points (a,fa), (b,fb), and (c,fc) with derivative at a of fpa.
+
+    If no minimizer can be found, return None.
+
+    """
+    # f(x) = A *(x-a)^3 + B*(x-a)^2 + C*(x-a) + D
+
+    with np.errstate(divide='raise', over='raise', invalid='raise'):
+        try:
+            C = fpa
+            db = b - a
+            dc = c - a
+            denom = (db * dc) ** 2 * (db - dc)
+            d1 = np.empty((2, 2))
+            d1[0, 0] = dc ** 2
+            d1[0, 1] = -db ** 2
+            d1[1, 0] = -dc ** 3
+            d1[1, 1] = db ** 3
+            [A, B] = np.dot(d1, np.asarray([fb - fa - C * db,
+                                            fc - fa - C * dc]).flatten())
+            A /= denom
+            B /= denom
+            radical = B * B - 3 * A * C
+            xmin = a + (-B + np.sqrt(radical)) / (3 * A)
+        except ArithmeticError:
+            return None
+    if not np.isfinite(xmin):
+        return None
+    return xmin
+
+
+def _quadmin(a, fa, fpa, b, fb):
+    """
+    Finds the minimizer for a quadratic polynomial that goes through
+    the points (a,fa), (b,fb) with derivative at a of fpa.
+
+    """
+    # f(x) = B*(x-a)^2 + C*(x-a) + D
+    with np.errstate(divide='raise', over='raise', invalid='raise'):
+        try:
+            D = fa
+            C = fpa
+            db = b - a * 1.0
+            B = (fb - D - C * db) / (db * db)
+            xmin = a - C / (2.0 * B)
+        except ArithmeticError:
+            return None
+    if not np.isfinite(xmin):
+        return None
+    return xmin
+
+
+def _zoom(a_lo, a_hi, phi_lo, phi_hi, derphi_lo,
+          phi, derphi, phi0, derphi0, c1, c2, extra_condition):
+    """Zoom stage of approximate linesearch satisfying strong Wolfe conditions.
+
+    Part of the optimization algorithm in `scalar_search_wolfe2`.
+
+    Notes
+    -----
+    Implements Algorithm 3.6 (zoom) in Wright and Nocedal,
+    'Numerical Optimization', 1999, pp. 61.
+
+    """
+
+    maxiter = 10
+    i = 0
+    delta1 = 0.2  # cubic interpolant check
+    delta2 = 0.1  # quadratic interpolant check
+    phi_rec = phi0
+    a_rec = 0
+    while True:
+        # interpolate to find a trial step length between a_lo and
+        # a_hi Need to choose interpolation here. Use cubic
+        # interpolation and then if the result is within delta *
+        # dalpha or outside of the interval bounded by a_lo or a_hi
+        # then use quadratic interpolation, if the result is still too
+        # close, then use bisection
+
+        dalpha = a_hi - a_lo
+        if dalpha < 0:
+            a, b = a_hi, a_lo
+        else:
+            a, b = a_lo, a_hi
+
+        # minimizer of cubic interpolant
+        # (uses phi_lo, derphi_lo, phi_hi, and the most recent value of phi)
+        #
+        # if the result is too close to the end points (or out of the
+        # interval), then use quadratic interpolation with phi_lo,
+        # derphi_lo and phi_hi if the result is still too close to the
+        # end points (or out of the interval) then use bisection
+
+        if (i > 0):
+            cchk = delta1 * dalpha
+            a_j = _cubicmin(a_lo, phi_lo, derphi_lo, a_hi, phi_hi,
+                            a_rec, phi_rec)
+        if (i == 0) or (a_j is None) or (a_j > b - cchk) or (a_j < a + cchk):
+            qchk = delta2 * dalpha
+            a_j = _quadmin(a_lo, phi_lo, derphi_lo, a_hi, phi_hi)
+            if (a_j is None) or (a_j > b-qchk) or (a_j < a+qchk):
+                a_j = a_lo + 0.5*dalpha
+
+        # Check new value of a_j
+
+        phi_aj = phi(a_j)
+        if (phi_aj > phi0 + c1*a_j*derphi0) or (phi_aj >= phi_lo):
+            phi_rec = phi_hi
+            a_rec = a_hi
+            a_hi = a_j
+            phi_hi = phi_aj
+        else:
+            derphi_aj = derphi(a_j)
+            if abs(derphi_aj) <= -c2*derphi0 and extra_condition(a_j, phi_aj):
+                a_star = a_j
+                val_star = phi_aj
+                valprime_star = derphi_aj
+                break
+            if derphi_aj*(a_hi - a_lo) >= 0:
+                phi_rec = phi_hi
+                a_rec = a_hi
+                a_hi = a_lo
+                phi_hi = phi_lo
+            else:
+                phi_rec = phi_lo
+                a_rec = a_lo
+            a_lo = a_j
+            phi_lo = phi_aj
+            derphi_lo = derphi_aj
+        i += 1
+        if (i > maxiter):
+            # Failed to find a conforming step size
+            a_star = None
+            val_star = None
+            valprime_star = None
+            break
+    return a_star, val_star, valprime_star
+
+
+#------------------------------------------------------------------------------
+# Armijo line and scalar searches
+#------------------------------------------------------------------------------
+
+def line_search_armijo(f, xk, pk, gfk, old_fval, args=(), c1=1e-4, alpha0=1):
+    """Minimize over alpha, the function ``f(xk+alpha pk)``.
+
+    Parameters
+    ----------
+    f : callable
+        Function to be minimized.
+    xk : array_like
+        Current point.
+    pk : array_like
+        Search direction.
+    gfk : array_like
+        Gradient of `f` at point `xk`.
+    old_fval : float
+        Value of `f` at point `xk`.
+    args : tuple, optional
+        Optional arguments.
+    c1 : float, optional
+        Value to control stopping criterion.
+    alpha0 : scalar, optional
+        Value of `alpha` at start of the optimization.
+
+    Returns
+    -------
+    alpha
+    f_count
+    f_val_at_alpha
+
+    Notes
+    -----
+    Uses the interpolation algorithm (Armijo backtracking) as suggested by
+    Wright and Nocedal in 'Numerical Optimization', 1999, pp. 56-57
+
+    """
+    xk = np.atleast_1d(xk)
+    fc = [0]
+
+    def phi(alpha1):
+        fc[0] += 1
+        return f(xk + alpha1*pk, *args)
+
+    if old_fval is None:
+        phi0 = phi(0.)
+    else:
+        phi0 = old_fval  # compute f(xk) -- done in past loop
+
+    derphi0 = np.dot(gfk, pk)
+    alpha, phi1 = scalar_search_armijo(phi, phi0, derphi0, c1=c1,
+                                       alpha0=alpha0)
+    return alpha, fc[0], phi1
+
+
+def line_search_BFGS(f, xk, pk, gfk, old_fval, args=(), c1=1e-4, alpha0=1):
+    """
+    Compatibility wrapper for `line_search_armijo`
+    """
+    r = line_search_armijo(f, xk, pk, gfk, old_fval, args=args, c1=c1,
+                           alpha0=alpha0)
+    return r[0], r[1], 0, r[2]
+
+
+def scalar_search_armijo(phi, phi0, derphi0, c1=1e-4, alpha0=1, amin=0):
+    """Minimize over alpha, the function ``phi(alpha)``.
+
+    Uses the interpolation algorithm (Armijo backtracking) as suggested by
+    Wright and Nocedal in 'Numerical Optimization', 1999, pp. 56-57
+
+    alpha > 0 is assumed to be a descent direction.
+
+    Returns
+    -------
+    alpha
+    phi1
+
+    """
+    phi_a0 = phi(alpha0)
+    if phi_a0 <= phi0 + c1*alpha0*derphi0:
+        return alpha0, phi_a0
+
+    # Otherwise, compute the minimizer of a quadratic interpolant:
+
+    alpha1 = -(derphi0) * alpha0**2 / 2.0 / (phi_a0 - phi0 - derphi0 * alpha0)
+    phi_a1 = phi(alpha1)
+
+    if (phi_a1 <= phi0 + c1*alpha1*derphi0):
+        return alpha1, phi_a1
+
+    # Otherwise, loop with cubic interpolation until we find an alpha which
+    # satisfies the first Wolfe condition (since we are backtracking, we will
+    # assume that the value of alpha is not too small and satisfies the second
+    # condition.
+
+    while alpha1 > amin:       # we are assuming alpha>0 is a descent direction
+        factor = alpha0**2 * alpha1**2 * (alpha1-alpha0)
+        a = alpha0**2 * (phi_a1 - phi0 - derphi0*alpha1) - \
+            alpha1**2 * (phi_a0 - phi0 - derphi0*alpha0)
+        a = a / factor
+        b = -alpha0**3 * (phi_a1 - phi0 - derphi0*alpha1) + \
+            alpha1**3 * (phi_a0 - phi0 - derphi0*alpha0)
+        b = b / factor
+
+        alpha2 = (-b + np.sqrt(abs(b**2 - 3 * a * derphi0))) / (3.0*a)
+        phi_a2 = phi(alpha2)
+
+        if (phi_a2 <= phi0 + c1*alpha2*derphi0):
+            return alpha2, phi_a2
+
+        if (alpha1 - alpha2) > alpha1 / 2.0 or (1 - alpha2/alpha1) < 0.96:
+            alpha2 = alpha1 / 2.0
+
+        alpha0 = alpha1
+        alpha1 = alpha2
+        phi_a0 = phi_a1
+        phi_a1 = phi_a2
+
+    # Failed to find a suitable step length
+    return None, phi_a1
+
+
+#------------------------------------------------------------------------------
+# Non-monotone line search for DF-SANE
+#------------------------------------------------------------------------------
+
+def _nonmonotone_line_search_cruz(f, x_k, d, prev_fs, eta,
+                                  gamma=1e-4, tau_min=0.1, tau_max=0.5):
+    """
+    Nonmonotone backtracking line search as described in [1]_
+
+    Parameters
+    ----------
+    f : callable
+        Function returning a tuple ``(f, F)`` where ``f`` is the value
+        of a merit function and ``F`` the residual.
+    x_k : ndarray
+        Initial position.
+    d : ndarray
+        Search direction.
+    prev_fs : float
+        List of previous merit function values. Should have ``len(prev_fs) <= M``
+        where ``M`` is the nonmonotonicity window parameter.
+    eta : float
+        Allowed merit function increase, see [1]_
+    gamma, tau_min, tau_max : float, optional
+        Search parameters, see [1]_
+
+    Returns
+    -------
+    alpha : float
+        Step length
+    xp : ndarray
+        Next position
+    fp : float
+        Merit function value at next position
+    Fp : ndarray
+        Residual at next position
+
+    References
+    ----------
+    [1] "Spectral residual method without gradient information for solving
+        large-scale nonlinear systems of equations." W. La Cruz,
+        J.M. Martinez, M. Raydan. Math. Comp. **75**, 1429 (2006).
+
+    """
+    f_k = prev_fs[-1]
+    f_bar = max(prev_fs)
+
+    alpha_p = 1
+    alpha_m = 1
+    alpha = 1
+
+    while True:
+        xp = x_k + alpha_p * d
+        fp, Fp = f(xp)
+
+        if fp <= f_bar + eta - gamma * alpha_p**2 * f_k:
+            alpha = alpha_p
+            break
+
+        alpha_tp = alpha_p**2 * f_k / (fp + (2*alpha_p - 1)*f_k)
+
+        xp = x_k - alpha_m * d
+        fp, Fp = f(xp)
+
+        if fp <= f_bar + eta - gamma * alpha_m**2 * f_k:
+            alpha = -alpha_m
+            break
+
+        alpha_tm = alpha_m**2 * f_k / (fp + (2*alpha_m - 1)*f_k)
+
+        alpha_p = np.clip(alpha_tp, tau_min * alpha_p, tau_max * alpha_p)
+        alpha_m = np.clip(alpha_tm, tau_min * alpha_m, tau_max * alpha_m)
+
+    return alpha, xp, fp, Fp
+
+
+def _nonmonotone_line_search_cheng(f, x_k, d, f_k, C, Q, eta,
+                                   gamma=1e-4, tau_min=0.1, tau_max=0.5,
+                                   nu=0.85):
+    """
+    Nonmonotone line search from [1]
+
+    Parameters
+    ----------
+    f : callable
+        Function returning a tuple ``(f, F)`` where ``f`` is the value
+        of a merit function and ``F`` the residual.
+    x_k : ndarray
+        Initial position.
+    d : ndarray
+        Search direction.
+    f_k : float
+        Initial merit function value.
+    C, Q : float
+        Control parameters. On the first iteration, give values
+        Q=1.0, C=f_k
+    eta : float
+        Allowed merit function increase, see [1]_
+    nu, gamma, tau_min, tau_max : float, optional
+        Search parameters, see [1]_
+
+    Returns
+    -------
+    alpha : float
+        Step length
+    xp : ndarray
+        Next position
+    fp : float
+        Merit function value at next position
+    Fp : ndarray
+        Residual at next position
+    C : float
+        New value for the control parameter C
+    Q : float
+        New value for the control parameter Q
+
+    References
+    ----------
+    .. [1] W. Cheng & D.-H. Li, ''A derivative-free nonmonotone line
+           search and its application to the spectral residual
+           method'', IMA J. Numer. Anal. 29, 814 (2009).
+
+    """
+    alpha_p = 1
+    alpha_m = 1
+    alpha = 1
+
+    while True:
+        xp = x_k + alpha_p * d
+        fp, Fp = f(xp)
+
+        if fp <= C + eta - gamma * alpha_p**2 * f_k:
+            alpha = alpha_p
+            break
+
+        alpha_tp = alpha_p**2 * f_k / (fp + (2*alpha_p - 1)*f_k)
+
+        xp = x_k - alpha_m * d
+        fp, Fp = f(xp)
+
+        if fp <= C + eta - gamma * alpha_m**2 * f_k:
+            alpha = -alpha_m
+            break
+
+        alpha_tm = alpha_m**2 * f_k / (fp + (2*alpha_m - 1)*f_k)
+
+        alpha_p = np.clip(alpha_tp, tau_min * alpha_p, tau_max * alpha_p)
+        alpha_m = np.clip(alpha_tm, tau_min * alpha_m, tau_max * alpha_m)
+
+    # Update C and Q
+    Q_next = nu * Q + 1
+    C = (nu * Q * (C + eta) + fp) / Q_next
+    Q = Q_next
+
+    return alpha, xp, fp, Fp, C, Q

venv/lib/python3.13/site-packages/scipy/optimize/_linprog.py

@@ -0,0 +1,733 @@
+"""
+A top-level linear programming interface.
+
+.. versionadded:: 0.15.0
+
+Functions
+---------
+.. autosummary::
+   :toctree: generated/
+
+    linprog
+    linprog_verbose_callback
+    linprog_terse_callback
+
+"""
+
+import numpy as np
+
+from ._optimize import OptimizeResult, OptimizeWarning
+from warnings import warn
+from ._linprog_highs import _linprog_highs
+from ._linprog_ip import _linprog_ip
+from ._linprog_simplex import _linprog_simplex
+from ._linprog_rs import _linprog_rs
+from ._linprog_doc import (_linprog_highs_doc, _linprog_ip_doc,  # noqa: F401
+                           _linprog_rs_doc, _linprog_simplex_doc,
+                           _linprog_highs_ipm_doc, _linprog_highs_ds_doc)
+from ._linprog_util import (
+    _parse_linprog, _presolve, _get_Abc, _LPProblem, _autoscale,
+    _postsolve, _check_result, _display_summary)
+from copy import deepcopy
+
+__all__ = ['linprog', 'linprog_verbose_callback', 'linprog_terse_callback']
+
+__docformat__ = "restructuredtext en"
+
+LINPROG_METHODS = [
+    'simplex', 'revised simplex', 'interior-point', 'highs', 'highs-ds', 'highs-ipm'
+]
+
+
+def linprog_verbose_callback(res):
+    """
+    A sample callback function demonstrating the linprog callback interface.
+    This callback produces detailed output to sys.stdout before each iteration
+    and after the final iteration of the simplex algorithm.
+
+    Parameters
+    ----------
+    res : A `scipy.optimize.OptimizeResult` consisting of the following fields:
+
+        x : 1-D array
+            The independent variable vector which optimizes the linear
+            programming problem.
+        fun : float
+            Value of the objective function.
+        success : bool
+            True if the algorithm succeeded in finding an optimal solution.
+        slack : 1-D array
+            The values of the slack variables. Each slack variable corresponds
+            to an inequality constraint. If the slack is zero, then the
+            corresponding constraint is active.
+        con : 1-D array
+            The (nominally zero) residuals of the equality constraints, that is,
+            ``b - A_eq @ x``
+        phase : int
+            The phase of the optimization being executed. In phase 1 a basic
+            feasible solution is sought and the T has an additional row
+            representing an alternate objective function.
+        status : int
+            An integer representing the exit status of the optimization:
+
+            ``0`` : Optimization terminated successfully
+
+            ``1`` : Iteration limit reached
+
+            ``2`` : Problem appears to be infeasible
+
+            ``3`` : Problem appears to be unbounded
+
+            ``4`` : Serious numerical difficulties encountered
+
+        nit : int
+            The number of iterations performed.
+        message : str
+            A string descriptor of the exit status of the optimization.
+    """
+    x = res['x']
+    fun = res['fun']
+    phase = res['phase']
+    status = res['status']
+    nit = res['nit']
+    message = res['message']
+    complete = res['complete']
+
+    saved_printoptions = np.get_printoptions()
+    np.set_printoptions(linewidth=500,
+                        formatter={'float': lambda x: f"{x: 12.4f}"})
+    if status:
+        print('--------- Simplex Early Exit -------\n')
+        print(f'The simplex method exited early with status {status:d}')
+        print(message)
+    elif complete:
+        print('--------- Simplex Complete --------\n')
+        print(f'Iterations required: {nit}')
+    else:
+        print(f'--------- Iteration {nit:d}  ---------\n')
+
+    if nit > 0:
+        if phase == 1:
+            print('Current Pseudo-Objective Value:')
+        else:
+            print('Current Objective Value:')
+        print('f = ', fun)
+        print()
+        print('Current Solution Vector:')
+        print('x = ', x)
+        print()
+
+    np.set_printoptions(**saved_printoptions)
+
+
+def linprog_terse_callback(res):
+    """
+    A sample callback function demonstrating the linprog callback interface.
+    This callback produces brief output to sys.stdout before each iteration
+    and after the final iteration of the simplex algorithm.
+
+    Parameters
+    ----------
+    res : A `scipy.optimize.OptimizeResult` consisting of the following fields:
+
+        x : 1-D array
+            The independent variable vector which optimizes the linear
+            programming problem.
+        fun : float
+            Value of the objective function.
+        success : bool
+            True if the algorithm succeeded in finding an optimal solution.
+        slack : 1-D array
+            The values of the slack variables. Each slack variable corresponds
+            to an inequality constraint. If the slack is zero, then the
+            corresponding constraint is active.
+        con : 1-D array
+            The (nominally zero) residuals of the equality constraints, that is,
+            ``b - A_eq @ x``.
+        phase : int
+            The phase of the optimization being executed. In phase 1 a basic
+            feasible solution is sought and the T has an additional row
+            representing an alternate objective function.
+        status : int
+            An integer representing the exit status of the optimization:
+
+            ``0`` : Optimization terminated successfully
+
+            ``1`` : Iteration limit reached
+
+            ``2`` : Problem appears to be infeasible
+
+            ``3`` : Problem appears to be unbounded
+
+            ``4`` : Serious numerical difficulties encountered
+
+        nit : int
+            The number of iterations performed.
+        message : str
+            A string descriptor of the exit status of the optimization.
+    """
+    nit = res['nit']
+    x = res['x']
+
+    if nit == 0:
+        print("Iter:   X:")
+    print(f"{nit: <5d}   ", end="")
+    print(x)
+
+
+def linprog(c, A_ub=None, b_ub=None, A_eq=None, b_eq=None,
+            bounds=(0, None), method='highs', callback=None,
+            options=None, x0=None, integrality=None):
+    r"""
+    Linear programming: minimize a linear objective function subject to linear
+    equality and inequality constraints.
+
+    Linear programming solves problems of the following form:
+
+    .. math::
+
+        \min_x \ & c^T x \\
+        \mbox{such that} \ & A_{ub} x \leq b_{ub},\\
+        & A_{eq} x = b_{eq},\\
+        & l \leq x \leq u ,
+
+    where :math:`x` is a vector of decision variables; :math:`c`,
+    :math:`b_{ub}`, :math:`b_{eq}`, :math:`l`, and :math:`u` are vectors; and
+    :math:`A_{ub}` and :math:`A_{eq}` are matrices.
+
+    Alternatively, that's:
+
+    - minimize ::
+
+        c @ x
+
+    - such that ::
+
+        A_ub @ x <= b_ub
+        A_eq @ x == b_eq
+        lb <= x <= ub
+
+    Note that by default ``lb = 0`` and ``ub = None``. Other bounds can be
+    specified with ``bounds``.
+
+    Parameters
+    ----------
+    c : 1-D array
+        The coefficients of the linear objective function to be minimized.
+    A_ub : 2-D array, optional
+        The inequality constraint matrix. Each row of ``A_ub`` specifies the
+        coefficients of a linear inequality constraint on ``x``.
+    b_ub : 1-D array, optional
+        The inequality constraint vector. Each element represents an
+        upper bound on the corresponding value of ``A_ub @ x``.
+    A_eq : 2-D array, optional
+        The equality constraint matrix. Each row of ``A_eq`` specifies the
+        coefficients of a linear equality constraint on ``x``.
+    b_eq : 1-D array, optional
+        The equality constraint vector. Each element of ``A_eq @ x`` must equal
+        the corresponding element of ``b_eq``.
+    bounds : sequence, optional
+        A sequence of ``(min, max)`` pairs for each element in ``x``, defining
+        the minimum and maximum values of that decision variable.
+        If a single tuple ``(min, max)`` is provided, then ``min`` and ``max``
+        will serve as bounds for all decision variables.
+        Use ``None`` to indicate that there is no bound. For instance, the
+        default bound ``(0, None)`` means that all decision variables are
+        non-negative, and the pair ``(None, None)`` means no bounds at all,
+        i.e. all variables are allowed to be any real.
+    method : str, optional
+        The algorithm used to solve the standard form problem.
+        The following are supported.
+
+        - :ref:`'highs' <optimize.linprog-highs>` (default)
+        - :ref:`'highs-ds' <optimize.linprog-highs-ds>`
+        - :ref:`'highs-ipm' <optimize.linprog-highs-ipm>`
+        - :ref:`'interior-point' <optimize.linprog-interior-point>` (legacy)
+        - :ref:`'revised simplex' <optimize.linprog-revised_simplex>` (legacy)
+        - :ref:`'simplex' <optimize.linprog-simplex>` (legacy)
+
+        The legacy methods are deprecated and will be removed in SciPy 1.11.0.
+    callback : callable, optional
+        If a callback function is provided, it will be called at least once per
+        iteration of the algorithm. The callback function must accept a single
+        `scipy.optimize.OptimizeResult` consisting of the following fields:
+
+        x : 1-D array
+            The current solution vector.
+        fun : float
+            The current value of the objective function ``c @ x``.
+        success : bool
+            ``True`` when the algorithm has completed successfully.
+        slack : 1-D array
+            The (nominally positive) values of the slack,
+            ``b_ub - A_ub @ x``.
+        con : 1-D array
+            The (nominally zero) residuals of the equality constraints,
+            ``b_eq - A_eq @ x``.
+        phase : int
+            The phase of the algorithm being executed.
+        status : int
+            An integer representing the status of the algorithm.
+
+            ``0`` : Optimization proceeding nominally.
+
+            ``1`` : Iteration limit reached.
+
+            ``2`` : Problem appears to be infeasible.
+
+            ``3`` : Problem appears to be unbounded.
+
+            ``4`` : Numerical difficulties encountered.
+
+        nit : int
+            The current iteration number.
+        message : str
+            A string descriptor of the algorithm status.
+
+        Callback functions are not currently supported by the HiGHS methods.
+
+    options : dict, optional
+        A dictionary of solver options. All methods accept the following
+        options:
+
+        maxiter : int
+            Maximum number of iterations to perform.
+            Default: see method-specific documentation.
+        disp : bool
+            Set to ``True`` to print convergence messages.
+            Default: ``False``.
+        presolve : bool
+            Set to ``False`` to disable automatic presolve.
+            Default: ``True``.
+
+        All methods except the HiGHS solvers also accept:
+
+        tol : float
+            A tolerance which determines when a residual is "close enough" to
+            zero to be considered exactly zero.
+        autoscale : bool
+            Set to ``True`` to automatically perform equilibration.
+            Consider using this option if the numerical values in the
+            constraints are separated by several orders of magnitude.
+            Default: ``False``.
+        rr : bool
+            Set to ``False`` to disable automatic redundancy removal.
+            Default: ``True``.
+        rr_method : string
+            Method used to identify and remove redundant rows from the
+            equality constraint matrix after presolve. For problems with
+            dense input, the available methods for redundancy removal are:
+
+            ``SVD``:
+                Repeatedly performs singular value decomposition on
+                the matrix, detecting redundant rows based on nonzeros
+                in the left singular vectors that correspond with
+                zero singular values. May be fast when the matrix is
+                nearly full rank.
+            ``pivot``:
+                Uses the algorithm presented in [5]_ to identify
+                redundant rows.
+            ``ID``:
+                Uses a randomized interpolative decomposition.
+                Identifies columns of the matrix transpose not used in
+                a full-rank interpolative decomposition of the matrix.
+            ``None``:
+                Uses ``svd`` if the matrix is nearly full rank, that is,
+                the difference between the matrix rank and the number
+                of rows is less than five. If not, uses ``pivot``. The
+                behavior of this default is subject to change without
+                prior notice.
+
+            Default: None.
+            For problems with sparse input, this option is ignored, and the
+            pivot-based algorithm presented in [5]_ is used.
+
+        For method-specific options, see
+        :func:`show_options('linprog') <show_options>`.
+
+    x0 : 1-D array, optional
+        Guess values of the decision variables, which will be refined by
+        the optimization algorithm. This argument is currently used only by the
+        :ref:`'revised simplex' <optimize.linprog-revised_simplex>` method,
+        and can only be used if `x0` represents a basic feasible solution.
+
+    integrality : 1-D array or int, optional
+        Indicates the type of integrality constraint on each decision variable.
+
+        ``0`` : Continuous variable; no integrality constraint.
+
+        ``1`` : Integer variable; decision variable must be an integer
+        within `bounds`.
+
+        ``2`` : Semi-continuous variable; decision variable must be within
+        `bounds` or take value ``0``.
+
+        ``3`` : Semi-integer variable; decision variable must be an integer
+        within `bounds` or take value ``0``.
+
+        By default, all variables are continuous.
+
+        For mixed integrality constraints, supply an array of shape ``c.shape``.
+        To infer a constraint on each decision variable from shorter inputs,
+        the argument will be broadcast to ``c.shape`` using `numpy.broadcast_to`.
+
+        This argument is currently used only by the
+        :ref:`'highs' <optimize.linprog-highs>` method and is ignored otherwise.
+
+    Returns
+    -------
+    res : OptimizeResult
+        A :class:`scipy.optimize.OptimizeResult` consisting of the fields
+        below. Note that the return types of the fields may depend on whether
+        the optimization was successful, therefore it is recommended to check
+        `OptimizeResult.status` before relying on the other fields:
+
+        x : 1-D array
+            The values of the decision variables that minimizes the
+            objective function while satisfying the constraints.
+        fun : float
+            The optimal value of the objective function ``c @ x``.
+        slack : 1-D array
+            The (nominally positive) values of the slack variables,
+            ``b_ub - A_ub @ x``.
+        con : 1-D array
+            The (nominally zero) residuals of the equality constraints,
+            ``b_eq - A_eq @ x``.
+        success : bool
+            ``True`` when the algorithm succeeds in finding an optimal
+            solution.
+        status : int
+            An integer representing the exit status of the algorithm.
+
+            ``0`` : Optimization terminated successfully.
+
+            ``1`` : Iteration limit reached.
+
+            ``2`` : Problem appears to be infeasible.
+
+            ``3`` : Problem appears to be unbounded.
+
+            ``4`` : Numerical difficulties encountered.
+
+        nit : int
+            The total number of iterations performed in all phases.
+        message : str
+            A string descriptor of the exit status of the algorithm.
+
+    See Also
+    --------
+    show_options : Additional options accepted by the solvers.
+
+    Notes
+    -----
+    This section describes the available solvers that can be selected by the
+    'method' parameter.
+
+    :ref:`'highs-ds' <optimize.linprog-highs-ds>`, and
+    :ref:`'highs-ipm' <optimize.linprog-highs-ipm>` are interfaces to the
+    HiGHS simplex and interior-point method solvers [13]_, respectively.
+    :ref:`'highs' <optimize.linprog-highs>` (default) chooses between
+    the two automatically. These are the fastest linear
+    programming solvers in SciPy, especially for large, sparse problems;
+    which of these two is faster is problem-dependent.
+    The other solvers are legacy methods and will be removed when `callback` is
+    supported by the HiGHS methods.
+
+    Method :ref:`'highs-ds' <optimize.linprog-highs-ds>`, is a wrapper of the C++ high
+    performance dual revised simplex implementation (HSOL) [13]_, [14]_.
+    Method :ref:`'highs-ipm' <optimize.linprog-highs-ipm>` is a wrapper of a C++
+    implementation of an **i**\ nterior-\ **p**\ oint **m**\ ethod [13]_; it
+    features a crossover routine, so it is as accurate as a simplex solver.
+    Method :ref:`'highs' <optimize.linprog-highs>` chooses between the two
+    automatically.
+    For new code involving `linprog`, we recommend explicitly choosing one of
+    these three method values.
+
+    .. versionadded:: 1.6.0
+
+    Method :ref:`'interior-point' <optimize.linprog-interior-point>`
+    uses the primal-dual path following algorithm
+    as outlined in [4]_. This algorithm supports sparse constraint matrices and
+    is typically faster than the simplex methods, especially for large, sparse
+    problems. Note, however, that the solution returned may be slightly less
+    accurate than those of the simplex methods and will not, in general,
+    correspond with a vertex of the polytope defined by the constraints.
+
+    .. versionadded:: 1.0.0
+
+    Method :ref:`'revised simplex' <optimize.linprog-revised_simplex>`
+    uses the revised simplex method as described in
+    [9]_, except that a factorization [11]_ of the basis matrix, rather than
+    its inverse, is efficiently maintained and used to solve the linear systems
+    at each iteration of the algorithm.
+
+    .. versionadded:: 1.3.0
+
+    Method :ref:`'simplex' <optimize.linprog-simplex>` uses a traditional,
+    full-tableau implementation of
+    Dantzig's simplex algorithm [1]_, [2]_ (*not* the
+    Nelder-Mead simplex). This algorithm is included for backwards
+    compatibility and educational purposes.
+
+    .. versionadded:: 0.15.0
+
+    Before applying :ref:`'interior-point' <optimize.linprog-interior-point>`,
+    :ref:`'revised simplex' <optimize.linprog-revised_simplex>`, or
+    :ref:`'simplex' <optimize.linprog-simplex>`,
+    a presolve procedure based on [8]_ attempts
+    to identify trivial infeasibilities, trivial unboundedness, and potential
+    problem simplifications. Specifically, it checks for:
+
+    - rows of zeros in ``A_eq`` or ``A_ub``, representing trivial constraints;
+    - columns of zeros in ``A_eq`` `and` ``A_ub``, representing unconstrained
+      variables;
+    - column singletons in ``A_eq``, representing fixed variables; and
+    - column singletons in ``A_ub``, representing simple bounds.
+
+    If presolve reveals that the problem is unbounded (e.g. an unconstrained
+    and unbounded variable has negative cost) or infeasible (e.g., a row of
+    zeros in ``A_eq`` corresponds with a nonzero in ``b_eq``), the solver
+    terminates with the appropriate status code. Note that presolve terminates
+    as soon as any sign of unboundedness is detected; consequently, a problem
+    may be reported as unbounded when in reality the problem is infeasible
+    (but infeasibility has not been detected yet). Therefore, if it is
+    important to know whether the problem is actually infeasible, solve the
+    problem again with option ``presolve=False``.
+
+    If neither infeasibility nor unboundedness are detected in a single pass
+    of the presolve, bounds are tightened where possible and fixed
+    variables are removed from the problem. Then, linearly dependent rows
+    of the ``A_eq`` matrix are removed, (unless they represent an
+    infeasibility) to avoid numerical difficulties in the primary solve
+    routine. Note that rows that are nearly linearly dependent (within a
+    prescribed tolerance) may also be removed, which can change the optimal
+    solution in rare cases. If this is a concern, eliminate redundancy from
+    your problem formulation and run with option ``rr=False`` or
+    ``presolve=False``.
+
+    Several potential improvements can be made here: additional presolve
+    checks outlined in [8]_ should be implemented, the presolve routine should
+    be run multiple times (until no further simplifications can be made), and
+    more of the efficiency improvements from [5]_ should be implemented in the
+    redundancy removal routines.
+
+    After presolve, the problem is transformed to standard form by converting
+    the (tightened) simple bounds to upper bound constraints, introducing
+    non-negative slack variables for inequality constraints, and expressing
+    unbounded variables as the difference between two non-negative variables.
+    Optionally, the problem is automatically scaled via equilibration [12]_.
+    The selected algorithm solves the standard form problem, and a
+    postprocessing routine converts the result to a solution to the original
+    problem.
+
+    References
+    ----------
+    .. [1] Dantzig, George B., Linear programming and extensions. Rand
+           Corporation Research Study Princeton Univ. Press, Princeton, NJ,
+           1963
+    .. [2] Hillier, S.H. and Lieberman, G.J. (1995), "Introduction to
+           Mathematical Programming", McGraw-Hill, Chapter 4.
+    .. [3] Bland, Robert G. New finite pivoting rules for the simplex method.
+           Mathematics of Operations Research (2), 1977: pp. 103-107.
+    .. [4] Andersen, Erling D., and Knud D. Andersen. "The MOSEK interior point
+           optimizer for linear programming: an implementation of the
+           homogeneous algorithm." High performance optimization. Springer US,
+           2000. 197-232.
+    .. [5] Andersen, Erling D. "Finding all linearly dependent rows in
+           large-scale linear programming." Optimization Methods and Software
+           6.3 (1995): 219-227.
+    .. [6] Freund, Robert M. "Primal-Dual Interior-Point Methods for Linear
+           Programming based on Newton's Method." Unpublished Course Notes,
+           March 2004. Available 2/25/2017 at
+           https://ocw.mit.edu/courses/sloan-school-of-management/15-084j-nonlinear-programming-spring-2004/lecture-notes/lec14_int_pt_mthd.pdf
+    .. [7] Fourer, Robert. "Solving Linear Programs by Interior-Point Methods."
+           Unpublished Course Notes, August 26, 2005. Available 2/25/2017 at
+           http://www.4er.org/CourseNotes/Book%20B/B-III.pdf
+    .. [8] Andersen, Erling D., and Knud D. Andersen. "Presolving in linear
+           programming." Mathematical Programming 71.2 (1995): 221-245.
+    .. [9] Bertsimas, Dimitris, and J. Tsitsiklis. "Introduction to linear
+           programming." Athena Scientific 1 (1997): 997.
+    .. [10] Andersen, Erling D., et al. Implementation of interior point
+            methods for large scale linear programming. HEC/Universite de
+            Geneve, 1996.
+    .. [11] Bartels, Richard H. "A stabilization of the simplex method."
+            Journal in  Numerische Mathematik 16.5 (1971): 414-434.
+    .. [12] Tomlin, J. A. "On scaling linear programming problems."
+            Mathematical Programming Study 4 (1975): 146-166.
+    .. [13] Huangfu, Q., Galabova, I., Feldmeier, M., and Hall, J. A. J.
+            "HiGHS - high performance software for linear optimization."
+            https://highs.dev/
+    .. [14] Huangfu, Q. and Hall, J. A. J. "Parallelizing the dual revised
+            simplex method." Mathematical Programming Computation, 10 (1),
+            119-142, 2018. DOI: 10.1007/s12532-017-0130-5
+
+    Examples
+    --------
+    Consider the following problem:
+
+    .. math::
+
+        \min_{x_0, x_1} \ -x_0 + 4x_1 & \\
+        \mbox{such that} \ -3x_0 + x_1 & \leq 6,\\
+        -x_0 - 2x_1 & \geq -4,\\
+        x_1 & \geq -3.
+
+    The problem is not presented in the form accepted by `linprog`. This is
+    easily remedied by converting the "greater than" inequality
+    constraint to a "less than" inequality constraint by
+    multiplying both sides by a factor of :math:`-1`. Note also that the last
+    constraint is really the simple bound :math:`-3 \leq x_1 \leq \infty`.
+    Finally, since there are no bounds on :math:`x_0`, we must explicitly
+    specify the bounds :math:`-\infty \leq x_0 \leq \infty`, as the
+    default is for variables to be non-negative. After collecting coeffecients
+    into arrays and tuples, the input for this problem is:
+
+    >>> from scipy.optimize import linprog
+    >>> c = [-1, 4]
+    >>> A = [[-3, 1], [1, 2]]
+    >>> b = [6, 4]
+    >>> x0_bounds = (None, None)
+    >>> x1_bounds = (-3, None)
+    >>> res = linprog(c, A_ub=A, b_ub=b, bounds=[x0_bounds, x1_bounds])
+    >>> res.fun
+    -22.0
+    >>> res.x
+    array([10., -3.])
+    >>> res.message
+    'Optimization terminated successfully. (HiGHS Status 7: Optimal)'
+
+    The marginals (AKA dual values / shadow prices / Lagrange multipliers)
+    and residuals (slacks) are also available.
+
+    >>> res.ineqlin
+      residual: [ 3.900e+01  0.000e+00]
+     marginals: [-0.000e+00 -1.000e+00]
+
+    For example, because the marginal associated with the second inequality
+    constraint is -1, we expect the optimal value of the objective function
+    to decrease by ``eps`` if we add a small amount ``eps`` to the right hand
+    side of the second inequality constraint:
+
+    >>> eps = 0.05
+    >>> b[1] += eps
+    >>> linprog(c, A_ub=A, b_ub=b, bounds=[x0_bounds, x1_bounds]).fun
+    -22.05
+
+    Also, because the residual on the first inequality constraint is 39, we
+    can decrease the right hand side of the first constraint by 39 without
+    affecting the optimal solution.
+
+    >>> b = [6, 4]  # reset to original values
+    >>> b[0] -= 39
+    >>> linprog(c, A_ub=A, b_ub=b, bounds=[x0_bounds, x1_bounds]).fun
+    -22.0
+
+    """
+
+    meth = method.lower()
+    methods = {"highs", "highs-ds", "highs-ipm",
+               "simplex", "revised simplex", "interior-point"}
+
+    if meth not in methods:
+        raise ValueError(f"Unknown solver '{method}'")
+
+    if x0 is not None and meth != "revised simplex":
+        warning_message = "x0 is used only when method is 'revised simplex'. "
+        warn(warning_message, OptimizeWarning, stacklevel=2)
+
+    if np.any(integrality) and not meth == "highs":
+        integrality = None
+        warning_message = ("Only `method='highs'` supports integer "
+                           "constraints. Ignoring `integrality`.")
+        warn(warning_message, OptimizeWarning, stacklevel=2)
+    elif np.any(integrality):
+        integrality = np.broadcast_to(integrality, np.shape(c))
+    else:
+        integrality = None
+
+    lp = _LPProblem(c, A_ub, b_ub, A_eq, b_eq, bounds, x0, integrality)
+    lp, solver_options = _parse_linprog(lp, options, meth)
+    tol = solver_options.get('tol', 1e-9)
+
+    # Give unmodified problem to HiGHS
+    if meth.startswith('highs'):
+        if callback is not None:
+            raise NotImplementedError("HiGHS solvers do not support the "
+                                      "callback interface.")
+        highs_solvers = {'highs-ipm': 'ipm', 'highs-ds': 'simplex',
+                         'highs': None}
+
+        sol = _linprog_highs(lp, solver=highs_solvers[meth],
+                             **solver_options)
+        sol['status'], sol['message'] = (
+            _check_result(sol['x'], sol['fun'], sol['status'], sol['slack'],
+                          sol['con'], lp.bounds, tol, sol['message'],
+                          integrality))
+        sol['success'] = sol['status'] == 0
+        return OptimizeResult(sol)
+
+    warn(f"`method='{meth}'` is deprecated and will be removed in SciPy "
+         "1.11.0. Please use one of the HiGHS solvers (e.g. "
+         "`method='highs'`) in new code.", DeprecationWarning, stacklevel=2)
+
+    iteration = 0
+    complete = False  # will become True if solved in presolve
+    undo = []
+
+    # Keep the original arrays to calculate slack/residuals for original
+    # problem.
+    lp_o = deepcopy(lp)
+
+    # Solve trivial problem, eliminate variables, tighten bounds, etc.
+    rr_method = solver_options.pop('rr_method', None)  # need to pop these;
+    rr = solver_options.pop('rr', True)  # they're not passed to methods
+    c0 = 0  # we might get a constant term in the objective
+    if solver_options.pop('presolve', True):
+        (lp, c0, x, undo, complete, status, message) = _presolve(lp, rr,
+                                                                 rr_method,
+                                                                 tol)
+
+    C, b_scale = 1, 1  # for trivial unscaling if autoscale is not used
+    postsolve_args = (lp_o._replace(bounds=lp.bounds), undo, C, b_scale)
+
+    if not complete:
+        A, b, c, c0, x0 = _get_Abc(lp, c0)
+        if solver_options.pop('autoscale', False):
+            A, b, c, x0, C, b_scale = _autoscale(A, b, c, x0)
+            postsolve_args = postsolve_args[:-2] + (C, b_scale)
+
+        if meth == 'simplex':
+            x, status, message, iteration = _linprog_simplex(
+                c, c0=c0, A=A, b=b, callback=callback,
+                postsolve_args=postsolve_args, **solver_options)
+        elif meth == 'interior-point':
+            x, status, message, iteration = _linprog_ip(
+                c, c0=c0, A=A, b=b, callback=callback,
+                postsolve_args=postsolve_args, **solver_options)
+        elif meth == 'revised simplex':
+            x, status, message, iteration = _linprog_rs(
+                c, c0=c0, A=A, b=b, x0=x0, callback=callback,
+                postsolve_args=postsolve_args, **solver_options)
+
+    # Eliminate artificial variables, re-introduce presolved variables, etc.
+    disp = solver_options.get('disp', False)
+
+    x, fun, slack, con = _postsolve(x, postsolve_args, complete)
+
+    status, message = _check_result(x, fun, status, slack, con, lp_o.bounds,
+                                    tol, message, integrality)
+
+    if disp:
+        _display_summary(message, status, fun, iteration)
+
+    sol = {
+        'x': x,
+        'fun': fun,
+        'slack': slack,
+        'con': con,
+        'status': status,
+        'message': message,
+        'nit': iteration,
+        'success': status == 0}
+
+    return OptimizeResult(sol)

venv/lib/python3.13/site-packages/scipy/optimize/_linprog_highs.py

@@ -0,0 +1,422 @@
+"""HiGHS Linear Optimization Methods
+
+Interface to HiGHS linear optimization software.
+https://highs.dev/
+
+.. versionadded:: 1.5.0
+
+References
+----------
+.. [1] Q. Huangfu and J.A.J. Hall. "Parallelizing the dual revised simplex
+           method." Mathematical Programming Computation, 10 (1), 119-142,
+           2018. DOI: 10.1007/s12532-017-0130-5
+
+"""
+
+import inspect
+import numpy as np
+from ._optimize import OptimizeWarning, OptimizeResult
+from warnings import warn
+from ._highspy._highs_wrapper import _highs_wrapper
+from ._highspy._core import(
+    kHighsInf,
+    HighsDebugLevel,
+    ObjSense,
+    HighsModelStatus,
+    simplex_constants as s_c,  # [1]
+)
+from scipy.sparse import csc_array, vstack, issparse
+
+# [1]: Directly importing from "._highspy._core.simplex_constants"
+# causes problems when reloading.
+# See https://github.com/scipy/scipy/pull/22869 for details.
+
+def _highs_to_scipy_status_message(highs_status, highs_message):
+    """Converts HiGHS status number/message to SciPy status number/message"""
+
+    scipy_statuses_messages = {
+        None: (4, "HiGHS did not provide a status code. "),
+        HighsModelStatus.kNotset: (4, ""),
+        HighsModelStatus.kLoadError: (4, ""),
+        HighsModelStatus.kModelError: (2, ""),
+        HighsModelStatus.kPresolveError: (4, ""),
+        HighsModelStatus.kSolveError: (4, ""),
+        HighsModelStatus.kPostsolveError: (4, ""),
+        HighsModelStatus.kModelEmpty: (4, ""),
+        HighsModelStatus.kObjectiveBound: (4, ""),
+        HighsModelStatus.kObjectiveTarget: (4, ""),
+        HighsModelStatus.kOptimal: (0, "Optimization terminated successfully. "),
+        HighsModelStatus.kTimeLimit: (1, "Time limit reached. "),
+        HighsModelStatus.kIterationLimit: (1, "Iteration limit reached. "),
+        HighsModelStatus.kInfeasible: (2, "The problem is infeasible. "),
+        HighsModelStatus.kUnbounded: (3, "The problem is unbounded. "),
+        HighsModelStatus.kUnboundedOrInfeasible: (4, "The problem is unbounded "
+                                                  "or infeasible. ")}
+    unrecognized = (4, "The HiGHS status code was not recognized. ")
+    scipy_status, scipy_message = (
+        scipy_statuses_messages.get(highs_status, unrecognized))
+    hstat = int(highs_status) if highs_status is not None else None
+    scipy_message = (f"{scipy_message}"
+                     f"(HiGHS Status {hstat}: {highs_message})")
+    return scipy_status, scipy_message
+
+
+def _replace_inf(x):
+    # Replace `np.inf` with kHighsInf
+    infs = np.isinf(x)
+    with np.errstate(invalid="ignore"):
+        x[infs] = np.sign(x[infs])*kHighsInf
+    return x
+
+
+def _convert_to_highs_enum(option, option_str, choices):
+    # If option is in the choices we can look it up, if not use
+    # the default value taken from function signature and warn:
+    try:
+        return choices[option.lower()]
+    except AttributeError:
+        return choices[option]
+    except KeyError:
+        sig = inspect.signature(_linprog_highs)
+        default_str = sig.parameters[option_str].default
+        warn(f"Option {option_str} is {option}, but only values in "
+             f"{set(choices.keys())} are allowed. Using default: "
+             f"{default_str}.",
+             OptimizeWarning, stacklevel=3)
+        return choices[default_str]
+
+
+def _linprog_highs(lp, solver, time_limit=None, presolve=True,
+                   disp=False, maxiter=None,
+                   dual_feasibility_tolerance=None,
+                   primal_feasibility_tolerance=None,
+                   ipm_optimality_tolerance=None,
+                   simplex_dual_edge_weight_strategy=None,
+                   mip_rel_gap=None,
+                   mip_max_nodes=None,
+                   **unknown_options):
+    r"""
+    Solve the following linear programming problem using one of the HiGHS
+    solvers:
+
+    User-facing documentation is in _linprog_doc.py.
+
+    Parameters
+    ----------
+    lp :  _LPProblem
+        A ``scipy.optimize._linprog_util._LPProblem`` ``namedtuple``.
+    solver : "ipm" or "simplex" or None
+        Which HiGHS solver to use.  If ``None``, "simplex" will be used.
+
+    Options
+    -------
+    maxiter : int
+        The maximum number of iterations to perform in either phase. For
+        ``solver='ipm'``, this does not include the number of crossover
+        iterations.  Default is the largest possible value for an ``int``
+        on the platform.
+    disp : bool
+        Set to ``True`` if indicators of optimization status are to be printed
+        to the console each iteration; default ``False``.
+    time_limit : float
+        The maximum time in seconds allotted to solve the problem; default is
+        the largest possible value for a ``double`` on the platform.
+    presolve : bool
+        Presolve attempts to identify trivial infeasibilities,
+        identify trivial unboundedness, and simplify the problem before
+        sending it to the main solver. It is generally recommended
+        to keep the default setting ``True``; set to ``False`` if presolve is
+        to be disabled.
+    dual_feasibility_tolerance : double
+        Dual feasibility tolerance.  Default is 1e-07.
+        The minimum of this and ``primal_feasibility_tolerance``
+        is used for the feasibility tolerance when ``solver='ipm'``.
+    primal_feasibility_tolerance : double
+        Primal feasibility tolerance.  Default is 1e-07.
+        The minimum of this and ``dual_feasibility_tolerance``
+        is used for the feasibility tolerance when ``solver='ipm'``.
+    ipm_optimality_tolerance : double
+        Optimality tolerance for ``solver='ipm'``.  Default is 1e-08.
+        Minimum possible value is 1e-12 and must be smaller than the largest
+        possible value for a ``double`` on the platform.
+    simplex_dual_edge_weight_strategy : str (default: None)
+        Strategy for simplex dual edge weights. The default, ``None``,
+        automatically selects one of the following.
+
+        ``'dantzig'`` uses Dantzig's original strategy of choosing the most
+        negative reduced cost.
+
+        ``'devex'`` uses the strategy described in [15]_.
+
+        ``steepest`` uses the exact steepest edge strategy as described in
+        [16]_.
+
+        ``'steepest-devex'`` begins with the exact steepest edge strategy
+        until the computation is too costly or inexact and then switches to
+        the devex method.
+
+        Currently, using ``None`` always selects ``'steepest-devex'``, but this
+        may change as new options become available.
+
+    mip_max_nodes : int
+        The maximum number of nodes allotted to solve the problem; default is
+        the largest possible value for a ``HighsInt`` on the platform.
+        Ignored if not using the MIP solver.
+    unknown_options : dict
+        Optional arguments not used by this particular solver. If
+        ``unknown_options`` is non-empty, a warning is issued listing all
+        unused options.
+
+    Returns
+    -------
+    sol : dict
+        A dictionary consisting of the fields:
+
+            x : 1D array
+                The values of the decision variables that minimizes the
+                objective function while satisfying the constraints.
+            fun : float
+                The optimal value of the objective function ``c @ x``.
+            slack : 1D array
+                The (nominally positive) values of the slack,
+                ``b_ub - A_ub @ x``.
+            con : 1D array
+                The (nominally zero) residuals of the equality constraints,
+                ``b_eq - A_eq @ x``.
+            success : bool
+                ``True`` when the algorithm succeeds in finding an optimal
+                solution.
+            status : int
+                An integer representing the exit status of the algorithm.
+
+                ``0`` : Optimization terminated successfully.
+
+                ``1`` : Iteration or time limit reached.
+
+                ``2`` : Problem appears to be infeasible.
+
+                ``3`` : Problem appears to be unbounded.
+
+                ``4`` : The HiGHS solver ran into a problem.
+
+            message : str
+                A string descriptor of the exit status of the algorithm.
+            nit : int
+                The total number of iterations performed.
+                For ``solver='simplex'``, this includes iterations in all
+                phases. For ``solver='ipm'``, this does not include
+                crossover iterations.
+            crossover_nit : int
+                The number of primal/dual pushes performed during the
+                crossover routine for ``solver='ipm'``.  This is ``0``
+                for ``solver='simplex'``.
+            ineqlin : OptimizeResult
+                Solution and sensitivity information corresponding to the
+                inequality constraints, `b_ub`. A dictionary consisting of the
+                fields:
+
+                residual : np.ndnarray
+                    The (nominally positive) values of the slack variables,
+                    ``b_ub - A_ub @ x``.  This quantity is also commonly
+                    referred to as "slack".
+
+                marginals : np.ndarray
+                    The sensitivity (partial derivative) of the objective
+                    function with respect to the right-hand side of the
+                    inequality constraints, `b_ub`.
+
+            eqlin : OptimizeResult
+                Solution and sensitivity information corresponding to the
+                equality constraints, `b_eq`.  A dictionary consisting of the
+                fields:
+
+                residual : np.ndarray
+                    The (nominally zero) residuals of the equality constraints,
+                    ``b_eq - A_eq @ x``.
+
+                marginals : np.ndarray
+                    The sensitivity (partial derivative) of the objective
+                    function with respect to the right-hand side of the
+                    equality constraints, `b_eq`.
+
+            lower, upper : OptimizeResult
+                Solution and sensitivity information corresponding to the
+                lower and upper bounds on decision variables, `bounds`.
+
+                residual : np.ndarray
+                    The (nominally positive) values of the quantity
+                    ``x - lb`` (lower) or ``ub - x`` (upper).
+
+                marginals : np.ndarray
+                    The sensitivity (partial derivative) of the objective
+                    function with respect to the lower and upper
+                    `bounds`.
+
+            mip_node_count : int
+                The number of subproblems or "nodes" solved by the MILP
+                solver. Only present when `integrality` is not `None`.
+
+            mip_dual_bound : float
+                The MILP solver's final estimate of the lower bound on the
+                optimal solution. Only present when `integrality` is not
+                `None`.
+
+            mip_gap : float
+                The difference between the final objective function value
+                and the final dual bound, scaled by the final objective
+                function value. Only present when `integrality` is not
+                `None`.
+
+    Notes
+    -----
+    The result fields `ineqlin`, `eqlin`, `lower`, and `upper` all contain
+    `marginals`, or partial derivatives of the objective function with respect
+    to the right-hand side of each constraint. These partial derivatives are
+    also referred to as "Lagrange multipliers", "dual values", and
+    "shadow prices". The sign convention of `marginals` is opposite that
+    of Lagrange multipliers produced by many nonlinear solvers.
+
+    References
+    ----------
+    .. [15] Harris, Paula MJ. "Pivot selection methods of the Devex LP code."
+            Mathematical programming 5.1 (1973): 1-28.
+    .. [16] Goldfarb, Donald, and John Ker Reid. "A practicable steepest-edge
+            simplex algorithm." Mathematical Programming 12.1 (1977): 361-371.
+    """
+    if unknown_options:
+        message = (f"Unrecognized options detected: {unknown_options}. "
+                   "These will be passed to HiGHS verbatim.")
+        warn(message, OptimizeWarning, stacklevel=3)
+
+    # Map options to HiGHS enum values
+    simplex_dual_edge_weight_strategy_enum = _convert_to_highs_enum(
+        simplex_dual_edge_weight_strategy,
+        'simplex_dual_edge_weight_strategy',
+        choices={'dantzig': \
+                 s_c.SimplexEdgeWeightStrategy.kSimplexEdgeWeightStrategyDantzig,
+                 'devex': \
+                 s_c.SimplexEdgeWeightStrategy.kSimplexEdgeWeightStrategyDevex,
+                 'steepest-devex': \
+                 s_c.SimplexEdgeWeightStrategy.kSimplexEdgeWeightStrategyChoose,
+                 'steepest': \
+                 s_c.SimplexEdgeWeightStrategy.kSimplexEdgeWeightStrategySteepestEdge,
+                 None: None})
+
+    c, A_ub, b_ub, A_eq, b_eq, bounds, x0, integrality = lp
+
+    lb, ub = bounds.T.copy()  # separate bounds, copy->C-cntgs
+    # highs_wrapper solves LHS <= A*x <= RHS, not equality constraints
+    with np.errstate(invalid="ignore"):
+        lhs_ub = -np.ones_like(b_ub)*np.inf  # LHS of UB constraints is -inf
+    rhs_ub = b_ub  # RHS of UB constraints is b_ub
+    lhs_eq = b_eq  # Equality constraint is inequality
+    rhs_eq = b_eq  # constraint with LHS=RHS
+    lhs = np.concatenate((lhs_ub, lhs_eq))
+    rhs = np.concatenate((rhs_ub, rhs_eq))
+
+    if issparse(A_ub) or issparse(A_eq):
+        A = vstack((A_ub, A_eq))
+    else:
+        A = np.vstack((A_ub, A_eq))
+    A = csc_array(A)
+
+    options = {
+        'presolve': presolve,
+        'sense': ObjSense.kMinimize,
+        'solver': solver,
+        'time_limit': time_limit,
+        'highs_debug_level': HighsDebugLevel.kHighsDebugLevelNone,
+        'dual_feasibility_tolerance': dual_feasibility_tolerance,
+        'ipm_optimality_tolerance': ipm_optimality_tolerance,
+        'log_to_console': disp,
+        'mip_max_nodes': mip_max_nodes,
+        'output_flag': disp,
+        'primal_feasibility_tolerance': primal_feasibility_tolerance,
+        'simplex_dual_edge_weight_strategy':
+            simplex_dual_edge_weight_strategy_enum,
+        'simplex_strategy': s_c.SimplexStrategy.kSimplexStrategyDual,
+        'ipm_iteration_limit': maxiter,
+        'simplex_iteration_limit': maxiter,
+        'mip_rel_gap': mip_rel_gap,
+    }
+    options.update(unknown_options)
+
+    # np.inf doesn't work; use very large constant
+    rhs = _replace_inf(rhs)
+    lhs = _replace_inf(lhs)
+    lb = _replace_inf(lb)
+    ub = _replace_inf(ub)
+
+    if integrality is None or np.sum(integrality) == 0:
+        integrality = np.empty(0)
+    else:
+        integrality = np.array(integrality)
+
+    res = _highs_wrapper(c, A.indptr, A.indices, A.data, lhs, rhs,
+                         lb, ub, integrality.astype(np.uint8), options)
+
+    # HiGHS represents constraints as lhs/rhs, so
+    # Ax + s = b => Ax = b - s
+    # and we need to split up s by A_ub and A_eq
+    if 'slack' in res:
+        slack = res['slack']
+        con = np.array(slack[len(b_ub):])
+        slack = np.array(slack[:len(b_ub)])
+    else:
+        slack, con = None, None
+
+    # lagrange multipliers for equalities/inequalities and upper/lower bounds
+    if 'lambda' in res:
+        lamda = res['lambda']
+        marg_ineqlin = np.array(lamda[:len(b_ub)])
+        marg_eqlin = np.array(lamda[len(b_ub):])
+        marg_upper = np.array(res['marg_bnds'][1, :])
+        marg_lower = np.array(res['marg_bnds'][0, :])
+    else:
+        marg_ineqlin, marg_eqlin = None, None
+        marg_upper, marg_lower = None, None
+
+    # this needs to be updated if we start choosing the solver intelligently
+
+    # Convert to scipy-style status and message
+    highs_status = res.get('status', None)
+    highs_message = res.get('message', None)
+    status, message = _highs_to_scipy_status_message(highs_status,
+                                                     highs_message)
+
+    x = res['x'] # is None if not set
+    sol = {'x': x,
+           'slack': slack,
+           'con': con,
+           'ineqlin': OptimizeResult({
+               'residual': slack,
+               'marginals': marg_ineqlin,
+           }),
+           'eqlin': OptimizeResult({
+               'residual': con,
+               'marginals': marg_eqlin,
+           }),
+           'lower': OptimizeResult({
+               'residual': None if x is None else x - lb,
+               'marginals': marg_lower,
+           }),
+           'upper': OptimizeResult({
+               'residual': None if x is None else ub - x,
+               'marginals': marg_upper
+            }),
+           'fun': res.get('fun'),
+           'status': status,
+           'success': res['status'] == HighsModelStatus.kOptimal,
+           'message': message,
+           'nit': res.get('simplex_nit', 0) or res.get('ipm_nit', 0),
+           'crossover_nit': res.get('crossover_nit'),
+           }
+
+    if np.any(x) and integrality is not None:
+        sol.update({
+            'mip_node_count': res.get('mip_node_count', 0),
+            'mip_dual_bound': res.get('mip_dual_bound', 0.0),
+            'mip_gap': res.get('mip_gap', 0.0),
+        })
+
+    return sol

venv/lib/python3.13/site-packages/scipy/optimize/_linprog_rs.py

@@ -0,0 +1,572 @@
+"""Revised simplex method for linear programming
+
+The *revised simplex* method uses the method described in [1]_, except
+that a factorization [2]_ of the basis matrix, rather than its inverse,
+is efficiently maintained and used to solve the linear systems at each
+iteration of the algorithm.
+
+.. versionadded:: 1.3.0
+
+References
+----------
+.. [1] Bertsimas, Dimitris, and J. Tsitsiklis. "Introduction to linear
+           programming." Athena Scientific 1 (1997): 997.
+.. [2] Bartels, Richard H. "A stabilization of the simplex method."
+            Journal in  Numerische Mathematik 16.5 (1971): 414-434.
+
+"""
+# Author: Matt Haberland
+
+import numpy as np
+from numpy.linalg import LinAlgError
+
+from scipy.linalg import solve
+from ._optimize import _check_unknown_options
+from ._bglu_dense import LU
+from ._bglu_dense import BGLU as BGLU
+from ._linprog_util import _postsolve
+from ._optimize import OptimizeResult
+
+
+def _phase_one(A, b, x0, callback, postsolve_args, maxiter, tol, disp,
+               maxupdate, mast, pivot):
+    """
+    The purpose of phase one is to find an initial basic feasible solution
+    (BFS) to the original problem.
+
+    Generates an auxiliary problem with a trivial BFS and an objective that
+    minimizes infeasibility of the original problem. Solves the auxiliary
+    problem using the main simplex routine (phase two). This either yields
+    a BFS to the original problem or determines that the original problem is
+    infeasible. If feasible, phase one detects redundant rows in the original
+    constraint matrix and removes them, then chooses additional indices as
+    necessary to complete a basis/BFS for the original problem.
+    """
+
+    m, n = A.shape
+    status = 0
+
+    # generate auxiliary problem to get initial BFS
+    A, b, c, basis, x, status = _generate_auxiliary_problem(A, b, x0, tol)
+
+    if status == 6:
+        residual = c.dot(x)
+        iter_k = 0
+        return x, basis, A, b, residual, status, iter_k
+
+    # solve auxiliary problem
+    phase_one_n = n
+    iter_k = 0
+    x, basis, status, iter_k = _phase_two(c, A, x, basis, callback,
+                                          postsolve_args,
+                                          maxiter, tol, disp,
+                                          maxupdate, mast, pivot,
+                                          iter_k, phase_one_n)
+
+    # check for infeasibility
+    residual = c.dot(x)
+    if status == 0 and residual > tol:
+        status = 2
+
+    # drive artificial variables out of basis
+    # TODO: test redundant row removal better
+    # TODO: make solve more efficient with BGLU? This could take a while.
+    keep_rows = np.ones(m, dtype=bool)
+    for basis_column in basis[basis >= n]:
+        B = A[:, basis]
+        try:
+            basis_finder = np.abs(solve(B, A))  # inefficient
+            pertinent_row = np.argmax(basis_finder[:, basis_column])
+            eligible_columns = np.ones(n, dtype=bool)
+            eligible_columns[basis[basis < n]] = 0
+            eligible_column_indices = np.where(eligible_columns)[0]
+            index = np.argmax(basis_finder[:, :n]
+                              [pertinent_row, eligible_columns])
+            new_basis_column = eligible_column_indices[index]
+            if basis_finder[pertinent_row, new_basis_column] < tol:
+                keep_rows[pertinent_row] = False
+            else:
+                basis[basis == basis_column] = new_basis_column
+        except LinAlgError:
+            status = 4
+
+    # form solution to original problem
+    A = A[keep_rows, :n]
+    basis = basis[keep_rows]
+    x = x[:n]
+    m = A.shape[0]
+    return x, basis, A, b, residual, status, iter_k
+
+
+def _get_more_basis_columns(A, basis):
+    """
+    Called when the auxiliary problem terminates with artificial columns in
+    the basis, which must be removed and replaced with non-artificial
+    columns. Finds additional columns that do not make the matrix singular.
+    """
+    m, n = A.shape
+
+    # options for inclusion are those that aren't already in the basis
+    a = np.arange(m+n)
+    bl = np.zeros(len(a), dtype=bool)
+    bl[basis] = 1
+    options = a[~bl]
+    options = options[options < n]  # and they have to be non-artificial
+
+    # form basis matrix
+    B = np.zeros((m, m))
+    B[:, 0:len(basis)] = A[:, basis]
+
+    if (basis.size > 0 and
+            np.linalg.matrix_rank(B[:, :len(basis)]) < len(basis)):
+        raise Exception("Basis has dependent columns")
+
+    rank = 0  # just enter the loop
+    for i in range(n):  # somewhat arbitrary, but we need another way out
+        # permute the options, and take as many as needed
+        new_basis = np.random.permutation(options)[:m-len(basis)]
+        B[:, len(basis):] = A[:, new_basis]  # update the basis matrix
+        rank = np.linalg.matrix_rank(B)      # check the rank
+        if rank == m:
+            break
+
+    return np.concatenate((basis, new_basis))
+
+
+def _generate_auxiliary_problem(A, b, x0, tol):
+    """
+    Modifies original problem to create an auxiliary problem with a trivial
+    initial basic feasible solution and an objective that minimizes
+    infeasibility in the original problem.
+
+    Conceptually, this is done by stacking an identity matrix on the right of
+    the original constraint matrix, adding artificial variables to correspond
+    with each of these new columns, and generating a cost vector that is all
+    zeros except for ones corresponding with each of the new variables.
+
+    A initial basic feasible solution is trivial: all variables are zero
+    except for the artificial variables, which are set equal to the
+    corresponding element of the right hand side `b`.
+
+    Running the simplex method on this auxiliary problem drives all of the
+    artificial variables - and thus the cost - to zero if the original problem
+    is feasible. The original problem is declared infeasible otherwise.
+
+    Much of the complexity below is to improve efficiency by using singleton
+    columns in the original problem where possible, thus generating artificial
+    variables only as necessary, and using an initial 'guess' basic feasible
+    solution.
+    """
+    status = 0
+    m, n = A.shape
+
+    if x0 is not None:
+        x = x0
+    else:
+        x = np.zeros(n)
+
+    r = b - A@x  # residual; this must be all zeros for feasibility
+
+    A[r < 0] = -A[r < 0]  # express problem with RHS positive for trivial BFS
+    b[r < 0] = -b[r < 0]  # to the auxiliary problem
+    r[r < 0] *= -1
+
+    # Rows which we will need to find a trivial way to zero.
+    # This should just be the rows where there is a nonzero residual.
+    # But then we would not necessarily have a column singleton in every row.
+    # This makes it difficult to find an initial basis.
+    if x0 is None:
+        nonzero_constraints = np.arange(m)
+    else:
+        nonzero_constraints = np.where(r > tol)[0]
+
+    # these are (at least some of) the initial basis columns
+    basis = np.where(np.abs(x) > tol)[0]
+
+    if len(nonzero_constraints) == 0 and len(basis) <= m:  # already a BFS
+        c = np.zeros(n)
+        basis = _get_more_basis_columns(A, basis)
+        return A, b, c, basis, x, status
+    elif (len(nonzero_constraints) > m - len(basis) or
+          np.any(x < 0)):  # can't get trivial BFS
+        c = np.zeros(n)
+        status = 6
+        return A, b, c, basis, x, status
+
+    # chooses existing columns appropriate for inclusion in initial basis
+    cols, rows = _select_singleton_columns(A, r)
+
+    # find the rows we need to zero that we _can_ zero with column singletons
+    i_tofix = np.isin(rows, nonzero_constraints)
+    # these columns can't already be in the basis, though
+    # we are going to add them to the basis and change the corresponding x val
+    i_notinbasis = np.logical_not(np.isin(cols, basis))
+    i_fix_without_aux = np.logical_and(i_tofix, i_notinbasis)
+    rows = rows[i_fix_without_aux]
+    cols = cols[i_fix_without_aux]
+
+    # indices of the rows we can only zero with auxiliary variable
+    # these rows will get a one in each auxiliary column
+    arows = nonzero_constraints[np.logical_not(
+                                np.isin(nonzero_constraints, rows))]
+    n_aux = len(arows)
+    acols = n + np.arange(n_aux)          # indices of auxiliary columns
+
+    basis_ng = np.concatenate((cols, acols))   # basis columns not from guess
+    basis_ng_rows = np.concatenate((rows, arows))  # rows we need to zero
+
+    # add auxiliary singleton columns
+    A = np.hstack((A, np.zeros((m, n_aux))))
+    A[arows, acols] = 1
+
+    # generate initial BFS
+    x = np.concatenate((x, np.zeros(n_aux)))
+    x[basis_ng] = r[basis_ng_rows]/A[basis_ng_rows, basis_ng]
+
+    # generate costs to minimize infeasibility
+    c = np.zeros(n_aux + n)
+    c[acols] = 1
+
+    # basis columns correspond with nonzeros in guess, those with column
+    # singletons we used to zero remaining constraints, and any additional
+    # columns to get a full set (m columns)
+    basis = np.concatenate((basis, basis_ng))
+    basis = _get_more_basis_columns(A, basis)  # add columns as needed
+
+    return A, b, c, basis, x, status
+
+
+def _select_singleton_columns(A, b):
+    """
+    Finds singleton columns for which the singleton entry is of the same sign
+    as the right-hand side; these columns are eligible for inclusion in an
+    initial basis. Determines the rows in which the singleton entries are
+    located. For each of these rows, returns the indices of the one singleton
+    column and its corresponding row.
+    """
+    # find indices of all singleton columns and corresponding row indices
+    column_indices = np.nonzero(np.sum(np.abs(A) != 0, axis=0) == 1)[0]
+    columns = A[:, column_indices]          # array of singleton columns
+    row_indices = np.zeros(len(column_indices), dtype=int)
+    nonzero_rows, nonzero_columns = np.nonzero(columns)
+    row_indices[nonzero_columns] = nonzero_rows   # corresponding row indices
+
+    # keep only singletons with entries that have same sign as RHS
+    # this is necessary because all elements of BFS must be non-negative
+    same_sign = A[row_indices, column_indices]*b[row_indices] >= 0
+    column_indices = column_indices[same_sign][::-1]
+    row_indices = row_indices[same_sign][::-1]
+    # Reversing the order so that steps below select rightmost columns
+    # for initial basis, which will tend to be slack variables. (If the
+    # guess corresponds with a basic feasible solution but a constraint
+    # is not satisfied with the corresponding slack variable zero, the slack
+    # variable must be basic.)
+
+    # for each row, keep rightmost singleton column with an entry in that row
+    unique_row_indices, first_columns = np.unique(row_indices,
+                                                  return_index=True)
+    return column_indices[first_columns], unique_row_indices
+
+
+def _find_nonzero_rows(A, tol):
+    """
+    Returns logical array indicating the locations of rows with at least
+    one nonzero element.
+    """
+    return np.any(np.abs(A) > tol, axis=1)
+
+
+def _select_enter_pivot(c_hat, bl, a, rule="bland", tol=1e-12):
+    """
+    Selects a pivot to enter the basis. Currently Bland's rule - the smallest
+    index that has a negative reduced cost - is the default.
+    """
+    if rule.lower() == "mrc":  # index with minimum reduced cost
+        return a[~bl][np.argmin(c_hat)]
+    else:  # smallest index w/ negative reduced cost
+        return a[~bl][c_hat < -tol][0]
+
+
+def _display_iter(phase, iteration, slack, con, fun):
+    """
+    Print indicators of optimization status to the console.
+    """
+    header = True if not iteration % 20 else False
+
+    if header:
+        print("Phase",
+              "Iteration",
+              "Minimum Slack      ",
+              "Constraint Residual",
+              "Objective          ")
+
+    # :<X.Y left aligns Y digits in X digit spaces
+    fmt = '{0:<6}{1:<10}{2:<20.13}{3:<20.13}{4:<20.13}'
+    try:
+        slack = np.min(slack)
+    except ValueError:
+        slack = "NA"
+    print(fmt.format(phase, iteration, slack, np.linalg.norm(con), fun))
+
+
+def _display_and_callback(phase_one_n, x, postsolve_args, status,
+                          iteration, disp, callback):
+    if phase_one_n is not None:
+        phase = 1
+        x_postsolve = x[:phase_one_n]
+    else:
+        phase = 2
+        x_postsolve = x
+    x_o, fun, slack, con = _postsolve(x_postsolve,
+                                      postsolve_args)
+
+    if callback is not None:
+        res = OptimizeResult({'x': x_o, 'fun': fun, 'slack': slack,
+                              'con': con, 'nit': iteration,
+                              'phase': phase, 'complete': False,
+                              'status': status, 'message': "",
+                              'success': False})
+        callback(res)
+    if disp:
+        _display_iter(phase, iteration, slack, con, fun)
+
+
+def _phase_two(c, A, x, b, callback, postsolve_args, maxiter, tol, disp,
+               maxupdate, mast, pivot, iteration=0, phase_one_n=None):
+    """
+    The heart of the simplex method. Beginning with a basic feasible solution,
+    moves to adjacent basic feasible solutions successively lower reduced cost.
+    Terminates when there are no basic feasible solutions with lower reduced
+    cost or if the problem is determined to be unbounded.
+
+    This implementation follows the revised simplex method based on LU
+    decomposition. Rather than maintaining a tableau or an inverse of the
+    basis matrix, we keep a factorization of the basis matrix that allows
+    efficient solution of linear systems while avoiding stability issues
+    associated with inverted matrices.
+    """
+    m, n = A.shape
+    status = 0
+    a = np.arange(n)                    # indices of columns of A
+    ab = np.arange(m)                   # indices of columns of B
+    if maxupdate:
+        # basis matrix factorization object; similar to B = A[:, b]
+        B = BGLU(A, b, maxupdate, mast)
+    else:
+        B = LU(A, b)
+
+    for iteration in range(iteration, maxiter):
+
+        if disp or callback is not None:
+            _display_and_callback(phase_one_n, x, postsolve_args, status,
+                                  iteration, disp, callback)
+
+        bl = np.zeros(len(a), dtype=bool)
+        bl[b] = 1
+
+        xb = x[b]       # basic variables
+        cb = c[b]       # basic costs
+
+        try:
+            v = B.solve(cb, transposed=True)    # similar to v = solve(B.T, cb)
+        except LinAlgError:
+            status = 4
+            break
+
+        # TODO: cythonize?
+        c_hat = c - v.dot(A)    # reduced cost
+        c_hat = c_hat[~bl]
+        # Above is much faster than:
+        # N = A[:, ~bl]                 # slow!
+        # c_hat = c[~bl] - v.T.dot(N)
+        # Can we perform the multiplication only on the nonbasic columns?
+
+        if np.all(c_hat >= -tol):  # all reduced costs positive -> terminate
+            break
+
+        j = _select_enter_pivot(c_hat, bl, a, rule=pivot, tol=tol)
+        u = B.solve(A[:, j])        # similar to u = solve(B, A[:, j])
+
+        i = u > tol                 # if none of the u are positive, unbounded
+        if not np.any(i):
+            status = 3
+            break
+
+        th = xb[i]/u[i]
+        l = np.argmin(th)           # implicitly selects smallest subscript
+        th_star = th[l]             # step size
+
+        x[b] = x[b] - th_star*u     # take step
+        x[j] = th_star
+        B.update(ab[i][l], j)       # modify basis
+        b = B.b                     # similar to b[ab[i][l]] =
+
+    else:
+        # If the end of the for loop is reached (without a break statement),
+        # then another step has been taken, so the iteration counter should
+        # increment, info should be displayed, and callback should be called.
+        iteration += 1
+        status = 1
+        if disp or callback is not None:
+            _display_and_callback(phase_one_n, x, postsolve_args, status,
+                                  iteration, disp, callback)
+
+    return x, b, status, iteration
+
+
+def _linprog_rs(c, c0, A, b, x0, callback, postsolve_args,
+                maxiter=5000, tol=1e-12, disp=False,
+                maxupdate=10, mast=False, pivot="mrc",
+                **unknown_options):
+    """
+    Solve the following linear programming problem via a two-phase
+    revised simplex algorithm.::
+
+        minimize:     c @ x
+
+        subject to:  A @ x == b
+                     0 <= x < oo
+
+    User-facing documentation is in _linprog_doc.py.
+
+    Parameters
+    ----------
+    c : 1-D array
+        Coefficients of the linear objective function to be minimized.
+    c0 : float
+        Constant term in objective function due to fixed (and eliminated)
+        variables. (Currently unused.)
+    A : 2-D array
+        2-D array which, when matrix-multiplied by ``x``, gives the values of
+        the equality constraints at ``x``.
+    b : 1-D array
+        1-D array of values representing the RHS of each equality constraint
+        (row) in ``A_eq``.
+    x0 : 1-D array, optional
+        Starting values of the independent variables, which will be refined by
+        the optimization algorithm. For the revised simplex method, these must
+        correspond with a basic feasible solution.
+    callback : callable, optional
+        If a callback function is provided, it will be called within each
+        iteration of the algorithm. The callback function must accept a single
+        `scipy.optimize.OptimizeResult` consisting of the following fields:
+
+            x : 1-D array
+                Current solution vector.
+            fun : float
+                Current value of the objective function ``c @ x``.
+            success : bool
+                True only when an algorithm has completed successfully,
+                so this is always False as the callback function is called
+                only while the algorithm is still iterating.
+            slack : 1-D array
+                The values of the slack variables. Each slack variable
+                corresponds to an inequality constraint. If the slack is zero,
+                the corresponding constraint is active.
+            con : 1-D array
+                The (nominally zero) residuals of the equality constraints,
+                that is, ``b - A_eq @ x``.
+            phase : int
+                The phase of the algorithm being executed.
+            status : int
+                For revised simplex, this is always 0 because if a different
+                status is detected, the algorithm terminates.
+            nit : int
+                The number of iterations performed.
+            message : str
+                A string descriptor of the exit status of the optimization.
+    postsolve_args : tuple
+        Data needed by _postsolve to convert the solution to the standard-form
+        problem into the solution to the original problem.
+
+    Options
+    -------
+    maxiter : int
+       The maximum number of iterations to perform in either phase.
+    tol : float
+        The tolerance which determines when a solution is "close enough" to
+        zero in Phase 1 to be considered a basic feasible solution or close
+        enough to positive to serve as an optimal solution.
+    disp : bool
+        Set to ``True`` if indicators of optimization status are to be printed
+        to the console each iteration.
+    maxupdate : int
+        The maximum number of updates performed on the LU factorization.
+        After this many updates is reached, the basis matrix is factorized
+        from scratch.
+    mast : bool
+        Minimize Amortized Solve Time. If enabled, the average time to solve
+        a linear system using the basis factorization is measured. Typically,
+        the average solve time will decrease with each successive solve after
+        initial factorization, as factorization takes much more time than the
+        solve operation (and updates). Eventually, however, the updated
+        factorization becomes sufficiently complex that the average solve time
+        begins to increase. When this is detected, the basis is refactorized
+        from scratch. Enable this option to maximize speed at the risk of
+        nondeterministic behavior. Ignored if ``maxupdate`` is 0.
+    pivot : "mrc" or "bland"
+        Pivot rule: Minimum Reduced Cost (default) or Bland's rule. Choose
+        Bland's rule if iteration limit is reached and cycling is suspected.
+    unknown_options : dict
+        Optional arguments not used by this particular solver. If
+        `unknown_options` is non-empty a warning is issued listing all
+        unused options.
+
+    Returns
+    -------
+    x : 1-D array
+        Solution vector.
+    status : int
+        An integer representing the exit status of the optimization::
+
+         0 : Optimization terminated successfully
+         1 : Iteration limit reached
+         2 : Problem appears to be infeasible
+         3 : Problem appears to be unbounded
+         4 : Numerical difficulties encountered
+         5 : No constraints; turn presolve on
+         6 : Guess x0 cannot be converted to a basic feasible solution
+
+    message : str
+        A string descriptor of the exit status of the optimization.
+    iteration : int
+        The number of iterations taken to solve the problem.
+    """
+
+    _check_unknown_options(unknown_options)
+
+    messages = ["Optimization terminated successfully.",
+                "Iteration limit reached.",
+                "The problem appears infeasible, as the phase one auxiliary "
+                "problem terminated successfully with a residual of {0:.1e}, "
+                "greater than the tolerance {1} required for the solution to "
+                "be considered feasible. Consider increasing the tolerance to "
+                "be greater than {0:.1e}. If this tolerance is unacceptably "
+                "large, the problem is likely infeasible.",
+                "The problem is unbounded, as the simplex algorithm found "
+                "a basic feasible solution from which there is a direction "
+                "with negative reduced cost in which all decision variables "
+                "increase.",
+                "Numerical difficulties encountered; consider trying "
+                "method='interior-point'.",
+                "Problems with no constraints are trivially solved; please "
+                "turn presolve on.",
+                "The guess x0 cannot be converted to a basic feasible "
+                "solution. "
+                ]
+
+    if A.size == 0:  # address test_unbounded_below_no_presolve_corrected
+        return np.zeros(c.shape), 5, messages[5], 0
+
+    x, basis, A, b, residual, status, iteration = (
+        _phase_one(A, b, x0, callback, postsolve_args,
+                   maxiter, tol, disp, maxupdate, mast, pivot))
+
+    if status == 0:
+        x, basis, status, iteration = _phase_two(c, A, x, basis, callback,
+                                                 postsolve_args,
+                                                 maxiter, tol, disp,
+                                                 maxupdate, mast, pivot,
+                                                 iteration)
+
+    return x, status, messages[status].format(residual, tol), iteration

venv/lib/python3.13/site-packages/scipy/optimize/_linprog_simplex.py

@@ -0,0 +1,663 @@
+"""Simplex method for  linear programming
+
+The *simplex* method uses a traditional, full-tableau implementation of
+Dantzig's simplex algorithm [1]_, [2]_ (*not* the Nelder-Mead simplex).
+This algorithm is included for backwards compatibility and educational
+purposes.
+
+    .. versionadded:: 0.15.0
+
+Warnings
+--------
+
+The simplex method may encounter numerical difficulties when pivot
+values are close to the specified tolerance. If encountered try
+remove any redundant constraints, change the pivot strategy to Bland's
+rule or increase the tolerance value.
+
+Alternatively, more robust methods maybe be used. See
+:ref:`'interior-point' <optimize.linprog-interior-point>` and
+:ref:`'revised simplex' <optimize.linprog-revised_simplex>`.
+
+References
+----------
+.. [1] Dantzig, George B., Linear programming and extensions. Rand
+       Corporation Research Study Princeton Univ. Press, Princeton, NJ,
+       1963
+.. [2] Hillier, S.H. and Lieberman, G.J. (1995), "Introduction to
+       Mathematical Programming", McGraw-Hill, Chapter 4.
+"""
+
+import numpy as np
+from warnings import warn
+from ._optimize import OptimizeResult, OptimizeWarning, _check_unknown_options
+from ._linprog_util import _postsolve
+
+
+def _pivot_col(T, tol=1e-9, bland=False):
+    """
+    Given a linear programming simplex tableau, determine the column
+    of the variable to enter the basis.
+
+    Parameters
+    ----------
+    T : 2-D array
+        A 2-D array representing the simplex tableau, T, corresponding to the
+        linear programming problem. It should have the form:
+
+        [[A[0, 0], A[0, 1], ..., A[0, n_total], b[0]],
+         [A[1, 0], A[1, 1], ..., A[1, n_total], b[1]],
+         .
+         .
+         .
+         [A[m, 0], A[m, 1], ..., A[m, n_total], b[m]],
+         [c[0],   c[1], ...,   c[n_total],    0]]
+
+        for a Phase 2 problem, or the form:
+
+        [[A[0, 0], A[0, 1], ..., A[0, n_total], b[0]],
+         [A[1, 0], A[1, 1], ..., A[1, n_total], b[1]],
+         .
+         .
+         .
+         [A[m, 0], A[m, 1], ..., A[m, n_total], b[m]],
+         [c[0],   c[1], ...,   c[n_total],   0],
+         [c'[0],  c'[1], ...,  c'[n_total],  0]]
+
+         for a Phase 1 problem (a problem in which a basic feasible solution is
+         sought prior to maximizing the actual objective. ``T`` is modified in
+         place by ``_solve_simplex``.
+    tol : float
+        Elements in the objective row larger than -tol will not be considered
+        for pivoting. Nominally this value is zero, but numerical issues
+        cause a tolerance about zero to be necessary.
+    bland : bool
+        If True, use Bland's rule for selection of the column (select the
+        first column with a negative coefficient in the objective row,
+        regardless of magnitude).
+
+    Returns
+    -------
+    status: bool
+        True if a suitable pivot column was found, otherwise False.
+        A return of False indicates that the linear programming simplex
+        algorithm is complete.
+    col: int
+        The index of the column of the pivot element.
+        If status is False, col will be returned as nan.
+    """
+    ma = np.ma.masked_where(T[-1, :-1] >= -tol, T[-1, :-1], copy=False)
+    if ma.count() == 0:
+        return False, np.nan
+    if bland:
+        # ma.mask is sometimes 0d
+        return True, np.nonzero(np.logical_not(np.atleast_1d(ma.mask)))[0][0]
+    return True, np.ma.nonzero(ma == ma.min())[0][0]
+
+
+def _pivot_row(T, basis, pivcol, phase, tol=1e-9, bland=False):
+    """
+    Given a linear programming simplex tableau, determine the row for the
+    pivot operation.
+
+    Parameters
+    ----------
+    T : 2-D array
+        A 2-D array representing the simplex tableau, T, corresponding to the
+        linear programming problem. It should have the form:
+
+        [[A[0, 0], A[0, 1], ..., A[0, n_total], b[0]],
+         [A[1, 0], A[1, 1], ..., A[1, n_total], b[1]],
+         .
+         .
+         .
+         [A[m, 0], A[m, 1], ..., A[m, n_total], b[m]],
+         [c[0],   c[1], ...,   c[n_total],    0]]
+
+        for a Phase 2 problem, or the form:
+
+        [[A[0, 0], A[0, 1], ..., A[0, n_total], b[0]],
+         [A[1, 0], A[1, 1], ..., A[1, n_total], b[1]],
+         .
+         .
+         .
+         [A[m, 0], A[m, 1], ..., A[m, n_total], b[m]],
+         [c[0],   c[1], ...,   c[n_total],   0],
+         [c'[0],  c'[1], ...,  c'[n_total],  0]]
+
+         for a Phase 1 problem (a Problem in which a basic feasible solution is
+         sought prior to maximizing the actual objective. ``T`` is modified in
+         place by ``_solve_simplex``.
+    basis : array
+        A list of the current basic variables.
+    pivcol : int
+        The index of the pivot column.
+    phase : int
+        The phase of the simplex algorithm (1 or 2).
+    tol : float
+        Elements in the pivot column smaller than tol will not be considered
+        for pivoting. Nominally this value is zero, but numerical issues
+        cause a tolerance about zero to be necessary.
+    bland : bool
+        If True, use Bland's rule for selection of the row (if more than one
+        row can be used, choose the one with the lowest variable index).
+
+    Returns
+    -------
+    status: bool
+        True if a suitable pivot row was found, otherwise False. A return
+        of False indicates that the linear programming problem is unbounded.
+    row: int
+        The index of the row of the pivot element. If status is False, row
+        will be returned as nan.
+    """
+    if phase == 1:
+        k = 2
+    else:
+        k = 1
+    ma = np.ma.masked_where(T[:-k, pivcol] <= tol, T[:-k, pivcol], copy=False)
+    if ma.count() == 0:
+        return False, np.nan
+    mb = np.ma.masked_where(T[:-k, pivcol] <= tol, T[:-k, -1], copy=False)
+    q = mb / ma
+    min_rows = np.ma.nonzero(q == q.min())[0]
+    if bland:
+        return True, min_rows[np.argmin(np.take(basis, min_rows))]
+    return True, min_rows[0]
+
+
+def _apply_pivot(T, basis, pivrow, pivcol, tol=1e-9):
+    """
+    Pivot the simplex tableau inplace on the element given by (pivrow, pivol).
+    The entering variable corresponds to the column given by pivcol forcing
+    the variable basis[pivrow] to leave the basis.
+
+    Parameters
+    ----------
+    T : 2-D array
+        A 2-D array representing the simplex tableau, T, corresponding to the
+        linear programming problem. It should have the form:
+
+        [[A[0, 0], A[0, 1], ..., A[0, n_total], b[0]],
+         [A[1, 0], A[1, 1], ..., A[1, n_total], b[1]],
+         .
+         .
+         .
+         [A[m, 0], A[m, 1], ..., A[m, n_total], b[m]],
+         [c[0],   c[1], ...,   c[n_total],    0]]
+
+        for a Phase 2 problem, or the form:
+
+        [[A[0, 0], A[0, 1], ..., A[0, n_total], b[0]],
+         [A[1, 0], A[1, 1], ..., A[1, n_total], b[1]],
+         .
+         .
+         .
+         [A[m, 0], A[m, 1], ..., A[m, n_total], b[m]],
+         [c[0],   c[1], ...,   c[n_total],   0],
+         [c'[0],  c'[1], ...,  c'[n_total],  0]]
+
+         for a Phase 1 problem (a problem in which a basic feasible solution is
+         sought prior to maximizing the actual objective. ``T`` is modified in
+         place by ``_solve_simplex``.
+    basis : 1-D array
+        An array of the indices of the basic variables, such that basis[i]
+        contains the column corresponding to the basic variable for row i.
+        Basis is modified in place by _apply_pivot.
+    pivrow : int
+        Row index of the pivot.
+    pivcol : int
+        Column index of the pivot.
+    """
+    basis[pivrow] = pivcol
+    pivval = T[pivrow, pivcol]
+    T[pivrow] = T[pivrow] / pivval
+    for irow in range(T.shape[0]):
+        if irow != pivrow:
+            T[irow] = T[irow] - T[pivrow] * T[irow, pivcol]
+
+    # The selected pivot should never lead to a pivot value less than the tol.
+    if np.isclose(pivval, tol, atol=0, rtol=1e4):
+        message = (
+            f"The pivot operation produces a pivot value of:{pivval: .1e}, "
+            "which is only slightly greater than the specified "
+            f"tolerance{tol: .1e}. This may lead to issues regarding the "
+            "numerical stability of the simplex method. "
+            "Removing redundant constraints, changing the pivot strategy "
+            "via Bland's rule or increasing the tolerance may "
+            "help reduce the issue.")
+        warn(message, OptimizeWarning, stacklevel=5)
+
+
+def _solve_simplex(T, n, basis, callback, postsolve_args,
+                   maxiter=1000, tol=1e-9, phase=2, bland=False, nit0=0,
+                   ):
+    """
+    Solve a linear programming problem in "standard form" using the Simplex
+    Method. Linear Programming is intended to solve the following problem form:
+
+    Minimize::
+
+        c @ x
+
+    Subject to::
+
+        A @ x == b
+            x >= 0
+
+    Parameters
+    ----------
+    T : 2-D array
+        A 2-D array representing the simplex tableau, T, corresponding to the
+        linear programming problem. It should have the form:
+
+        [[A[0, 0], A[0, 1], ..., A[0, n_total], b[0]],
+         [A[1, 0], A[1, 1], ..., A[1, n_total], b[1]],
+         .
+         .
+         .
+         [A[m, 0], A[m, 1], ..., A[m, n_total], b[m]],
+         [c[0],   c[1], ...,   c[n_total],    0]]
+
+        for a Phase 2 problem, or the form:
+
+        [[A[0, 0], A[0, 1], ..., A[0, n_total], b[0]],
+         [A[1, 0], A[1, 1], ..., A[1, n_total], b[1]],
+         .
+         .
+         .
+         [A[m, 0], A[m, 1], ..., A[m, n_total], b[m]],
+         [c[0],   c[1], ...,   c[n_total],   0],
+         [c'[0],  c'[1], ...,  c'[n_total],  0]]
+
+         for a Phase 1 problem (a problem in which a basic feasible solution is
+         sought prior to maximizing the actual objective. ``T`` is modified in
+         place by ``_solve_simplex``.
+    n : int
+        The number of true variables in the problem.
+    basis : 1-D array
+        An array of the indices of the basic variables, such that basis[i]
+        contains the column corresponding to the basic variable for row i.
+        Basis is modified in place by _solve_simplex
+    callback : callable, optional
+        If a callback function is provided, it will be called within each
+        iteration of the algorithm. The callback must accept a
+        `scipy.optimize.OptimizeResult` consisting of the following fields:
+
+            x : 1-D array
+                Current solution vector
+            fun : float
+                Current value of the objective function
+            success : bool
+                True only when a phase has completed successfully. This
+                will be False for most iterations.
+            slack : 1-D array
+                The values of the slack variables. Each slack variable
+                corresponds to an inequality constraint. If the slack is zero,
+                the corresponding constraint is active.
+            con : 1-D array
+                The (nominally zero) residuals of the equality constraints,
+                that is, ``b - A_eq @ x``
+            phase : int
+                The phase of the optimization being executed. In phase 1 a basic
+                feasible solution is sought and the T has an additional row
+                representing an alternate objective function.
+            status : int
+                An integer representing the exit status of the optimization::
+
+                     0 : Optimization terminated successfully
+                     1 : Iteration limit reached
+                     2 : Problem appears to be infeasible
+                     3 : Problem appears to be unbounded
+                     4 : Serious numerical difficulties encountered
+
+            nit : int
+                The number of iterations performed.
+            message : str
+                A string descriptor of the exit status of the optimization.
+    postsolve_args : tuple
+        Data needed by _postsolve to convert the solution to the standard-form
+        problem into the solution to the original problem.
+    maxiter : int
+        The maximum number of iterations to perform before aborting the
+        optimization.
+    tol : float
+        The tolerance which determines when a solution is "close enough" to
+        zero in Phase 1 to be considered a basic feasible solution or close
+        enough to positive to serve as an optimal solution.
+    phase : int
+        The phase of the optimization being executed. In phase 1 a basic
+        feasible solution is sought and the T has an additional row
+        representing an alternate objective function.
+    bland : bool
+        If True, choose pivots using Bland's rule [3]_. In problems which
+        fail to converge due to cycling, using Bland's rule can provide
+        convergence at the expense of a less optimal path about the simplex.
+    nit0 : int
+        The initial iteration number used to keep an accurate iteration total
+        in a two-phase problem.
+
+    Returns
+    -------
+    nit : int
+        The number of iterations. Used to keep an accurate iteration total
+        in the two-phase problem.
+    status : int
+        An integer representing the exit status of the optimization::
+
+         0 : Optimization terminated successfully
+         1 : Iteration limit reached
+         2 : Problem appears to be infeasible
+         3 : Problem appears to be unbounded
+         4 : Serious numerical difficulties encountered
+
+    """
+    nit = nit0
+    status = 0
+    message = ''
+    complete = False
+
+    if phase == 1:
+        m = T.shape[1]-2
+    elif phase == 2:
+        m = T.shape[1]-1
+    else:
+        raise ValueError("Argument 'phase' to _solve_simplex must be 1 or 2")
+
+    if phase == 2:
+        # Check if any artificial variables are still in the basis.
+        # If yes, check if any coefficients from this row and a column
+        # corresponding to one of the non-artificial variable is non-zero.
+        # If found, pivot at this term. If not, start phase 2.
+        # Do this for all artificial variables in the basis.
+        # Ref: "An Introduction to Linear Programming and Game Theory"
+        # by Paul R. Thie, Gerard E. Keough, 3rd Ed,
+        # Chapter 3.7 Redundant Systems (pag 102)
+        for pivrow in [row for row in range(basis.size)
+                       if basis[row] > T.shape[1] - 2]:
+            non_zero_row = [col for col in range(T.shape[1] - 1)
+                            if abs(T[pivrow, col]) > tol]
+            if len(non_zero_row) > 0:
+                pivcol = non_zero_row[0]
+                _apply_pivot(T, basis, pivrow, pivcol, tol)
+                nit += 1
+
+    if len(basis[:m]) == 0:
+        solution = np.empty(T.shape[1] - 1, dtype=np.float64)
+    else:
+        solution = np.empty(max(T.shape[1] - 1, max(basis[:m]) + 1),
+                            dtype=np.float64)
+
+    while not complete:
+        # Find the pivot column
+        pivcol_found, pivcol = _pivot_col(T, tol, bland)
+        if not pivcol_found:
+            pivcol = np.nan
+            pivrow = np.nan
+            status = 0
+            complete = True
+        else:
+            # Find the pivot row
+            pivrow_found, pivrow = _pivot_row(T, basis, pivcol, phase, tol, bland)
+            if not pivrow_found:
+                status = 3
+                complete = True
+
+        if callback is not None:
+            solution[:] = 0
+            solution[basis[:n]] = T[:n, -1]
+            x = solution[:m]
+            x, fun, slack, con = _postsolve(
+                x, postsolve_args
+            )
+            res = OptimizeResult({
+                'x': x,
+                'fun': fun,
+                'slack': slack,
+                'con': con,
+                'status': status,
+                'message': message,
+                'nit': nit,
+                'success': status == 0 and complete,
+                'phase': phase,
+                'complete': complete,
+                })
+            callback(res)
+
+        if not complete:
+            if nit >= maxiter:
+                # Iteration limit exceeded
+                status = 1
+                complete = True
+            else:
+                _apply_pivot(T, basis, pivrow, pivcol, tol)
+                nit += 1
+    return nit, status
+
+
+def _linprog_simplex(c, c0, A, b, callback, postsolve_args,
+                     maxiter=1000, tol=1e-9, disp=False, bland=False,
+                     **unknown_options):
+    """
+    Minimize a linear objective function subject to linear equality and
+    non-negativity constraints using the two phase simplex method.
+    Linear programming is intended to solve problems of the following form:
+
+    Minimize::
+
+        c @ x
+
+    Subject to::
+
+        A @ x == b
+            x >= 0
+
+    User-facing documentation is in _linprog_doc.py.
+
+    Parameters
+    ----------
+    c : 1-D array
+        Coefficients of the linear objective function to be minimized.
+    c0 : float
+        Constant term in objective function due to fixed (and eliminated)
+        variables. (Purely for display.)
+    A : 2-D array
+        2-D array such that ``A @ x``, gives the values of the equality
+        constraints at ``x``.
+    b : 1-D array
+        1-D array of values representing the right hand side of each equality
+        constraint (row) in ``A``.
+    callback : callable, optional
+        If a callback function is provided, it will be called within each
+        iteration of the algorithm. The callback function must accept a single
+        `scipy.optimize.OptimizeResult` consisting of the following fields:
+
+            x : 1-D array
+                Current solution vector
+            fun : float
+                Current value of the objective function
+            success : bool
+                True when an algorithm has completed successfully.
+            slack : 1-D array
+                The values of the slack variables. Each slack variable
+                corresponds to an inequality constraint. If the slack is zero,
+                the corresponding constraint is active.
+            con : 1-D array
+                The (nominally zero) residuals of the equality constraints,
+                that is, ``b - A_eq @ x``
+            phase : int
+                The phase of the algorithm being executed.
+            status : int
+                An integer representing the status of the optimization::
+
+                     0 : Algorithm proceeding nominally
+                     1 : Iteration limit reached
+                     2 : Problem appears to be infeasible
+                     3 : Problem appears to be unbounded
+                     4 : Serious numerical difficulties encountered
+            nit : int
+                The number of iterations performed.
+            message : str
+                A string descriptor of the exit status of the optimization.
+    postsolve_args : tuple
+        Data needed by _postsolve to convert the solution to the standard-form
+        problem into the solution to the original problem.
+
+    Options
+    -------
+    maxiter : int
+       The maximum number of iterations to perform.
+    disp : bool
+        If True, print exit status message to sys.stdout
+    tol : float
+        The tolerance which determines when a solution is "close enough" to
+        zero in Phase 1 to be considered a basic feasible solution or close
+        enough to positive to serve as an optimal solution.
+    bland : bool
+        If True, use Bland's anti-cycling rule [3]_ to choose pivots to
+        prevent cycling. If False, choose pivots which should lead to a
+        converged solution more quickly. The latter method is subject to
+        cycling (non-convergence) in rare instances.
+    unknown_options : dict
+        Optional arguments not used by this particular solver. If
+        `unknown_options` is non-empty a warning is issued listing all
+        unused options.
+
+    Returns
+    -------
+    x : 1-D array
+        Solution vector.
+    status : int
+        An integer representing the exit status of the optimization::
+
+         0 : Optimization terminated successfully
+         1 : Iteration limit reached
+         2 : Problem appears to be infeasible
+         3 : Problem appears to be unbounded
+         4 : Serious numerical difficulties encountered
+
+    message : str
+        A string descriptor of the exit status of the optimization.
+    iteration : int
+        The number of iterations taken to solve the problem.
+
+    References
+    ----------
+    .. [1] Dantzig, George B., Linear programming and extensions. Rand
+           Corporation Research Study Princeton Univ. Press, Princeton, NJ,
+           1963
+    .. [2] Hillier, S.H. and Lieberman, G.J. (1995), "Introduction to
+           Mathematical Programming", McGraw-Hill, Chapter 4.
+    .. [3] Bland, Robert G. New finite pivoting rules for the simplex method.
+           Mathematics of Operations Research (2), 1977: pp. 103-107.
+
+
+    Notes
+    -----
+    The expected problem formulation differs between the top level ``linprog``
+    module and the method specific solvers. The method specific solvers expect a
+    problem in standard form:
+
+    Minimize::
+
+        c @ x
+
+    Subject to::
+
+        A @ x == b
+            x >= 0
+
+    Whereas the top level ``linprog`` module expects a problem of form:
+
+    Minimize::
+
+        c @ x
+
+    Subject to::
+
+        A_ub @ x <= b_ub
+        A_eq @ x == b_eq
+         lb <= x <= ub
+
+    where ``lb = 0`` and ``ub = None`` unless set in ``bounds``.
+
+    The original problem contains equality, upper-bound and variable constraints
+    whereas the method specific solver requires equality constraints and
+    variable non-negativity.
+
+    ``linprog`` module converts the original problem to standard form by
+    converting the simple bounds to upper bound constraints, introducing
+    non-negative slack variables for inequality constraints, and expressing
+    unbounded variables as the difference between two non-negative variables.
+    """
+    _check_unknown_options(unknown_options)
+
+    status = 0
+    messages = {0: "Optimization terminated successfully.",
+                1: "Iteration limit reached.",
+                2: "Optimization failed. Unable to find a feasible"
+                   " starting point.",
+                3: "Optimization failed. The problem appears to be unbounded.",
+                4: "Optimization failed. Singular matrix encountered."}
+
+    n, m = A.shape
+
+    # All constraints must have b >= 0.
+    is_negative_constraint = np.less(b, 0)
+    A[is_negative_constraint] *= -1
+    b[is_negative_constraint] *= -1
+
+    # As all constraints are equality constraints the artificial variables
+    # will also be basic variables.
+    av = np.arange(n) + m
+    basis = av.copy()
+
+    # Format the phase one tableau by adding artificial variables and stacking
+    # the constraints, the objective row and pseudo-objective row.
+    row_constraints = np.hstack((A, np.eye(n), b[:, np.newaxis]))
+    row_objective = np.hstack((c, np.zeros(n), c0))
+    row_pseudo_objective = -row_constraints.sum(axis=0)
+    row_pseudo_objective[av] = 0
+    T = np.vstack((row_constraints, row_objective, row_pseudo_objective))
+
+    nit1, status = _solve_simplex(T, n, basis, callback=callback,
+                                  postsolve_args=postsolve_args,
+                                  maxiter=maxiter, tol=tol, phase=1,
+                                  bland=bland
+                                  )
+    # if pseudo objective is zero, remove the last row from the tableau and
+    # proceed to phase 2
+    nit2 = nit1
+    if abs(T[-1, -1]) < tol:
+        # Remove the pseudo-objective row from the tableau
+        T = T[:-1, :]
+        # Remove the artificial variable columns from the tableau
+        T = np.delete(T, av, 1)
+    else:
+        # Failure to find a feasible starting point
+        status = 2
+        messages[status] = (
+            "Phase 1 of the simplex method failed to find a feasible "
+            "solution. The pseudo-objective function evaluates to "
+            f"{abs(T[-1, -1]):.1e} "
+            f"which exceeds the required tolerance of {tol} for a solution to be "
+            "considered 'close enough' to zero to be a basic solution. "
+            "Consider increasing the tolerance to be greater than "
+            f"{abs(T[-1, -1]):.1e}. "
+            "If this tolerance is unacceptably large the problem may be "
+            "infeasible."
+        )
+
+    if status == 0:
+        # Phase 2
+        nit2, status = _solve_simplex(T, n, basis, callback=callback,
+                                      postsolve_args=postsolve_args,
+                                      maxiter=maxiter, tol=tol, phase=2,
+                                      bland=bland, nit0=nit1
+                                      )
+
+    solution = np.zeros(n + m)
+    solution[basis[:n]] = T[:n, -1]
+    x = solution[:m]
+
+    return x, status, messages[status], int(nit2)

venv/lib/python3.13/site-packages/scipy/optimize/_lsq/__init__.py

@@ -0,0 +1,5 @@
+"""This module contains least-squares algorithms."""
+from .least_squares import least_squares
+from .lsq_linear import lsq_linear
+
+__all__ = ['least_squares', 'lsq_linear']