Fixed database typo and removed unnecessary class identifier.

venv/Lib/site-packages/scipy/optimize/_trustregion_krylov.py

@@ -0,0 +1,65 @@
+from ._trustregion import (_minimize_trust_region)
+from ._trlib import (get_trlib_quadratic_subproblem)
+
+__all__ = ['_minimize_trust_krylov']
+
+def _minimize_trust_krylov(fun, x0, args=(), jac=None, hess=None, hessp=None,
+                           inexact=True, **trust_region_options):
+    """
+    Minimization of a scalar function of one or more variables using
+    a nearly exact trust-region algorithm that only requires matrix
+    vector products with the hessian matrix.
+
+    .. versionadded:: 1.0.0
+
+    Options
+    -------
+    inexact : bool, optional
+        Accuracy to solve subproblems. If True requires less nonlinear
+        iterations, but more vector products.
+    """
+
+    if jac is None:
+        raise ValueError('Jacobian is required for trust region ',
+                         'exact minimization.')
+    if hess is None and hessp is None:
+        raise ValueError('Either the Hessian or the Hessian-vector product '
+                         'is required for Krylov trust-region minimization')
+
+    # tol_rel specifies the termination tolerance relative to the initial
+    # gradient norm in the Krylov subspace iteration.
+
+    # - tol_rel_i specifies the tolerance for interior convergence.
+    # - tol_rel_b specifies the tolerance for boundary convergence.
+    #   in nonlinear programming applications it is not necessary to solve
+    #   the boundary case as exact as the interior case.
+
+    # - setting tol_rel_i=-2 leads to a forcing sequence in the Krylov
+    #   subspace iteration leading to quadratic convergence if eventually
+    #   the trust region stays inactive.
+    # - setting tol_rel_b=-3 leads to a forcing sequence in the Krylov
+    #   subspace iteration leading to superlinear convergence as long
+    #   as the iterates hit the trust region boundary.
+
+    # For details consult the documentation of trlib_krylov_min
+    # in _trlib/trlib_krylov.h
+    #
+    # Optimality of this choice of parameters among a range of possibilities
+    # has been tested on the unconstrained subset of the CUTEst library.
+
+    if inexact:
+        return _minimize_trust_region(fun, x0, args=args, jac=jac,
+                                      hess=hess, hessp=hessp,
+                                      subproblem=get_trlib_quadratic_subproblem(
+                                          tol_rel_i=-2.0, tol_rel_b=-3.0,
+                                          disp=trust_region_options.get('disp', False)
+                                          ),
+                                      **trust_region_options)
+    else:
+        return _minimize_trust_region(fun, x0, args=args, jac=jac,
+                                      hess=hess, hessp=hessp,
+                                      subproblem=get_trlib_quadratic_subproblem(
+                                          tol_rel_i=1e-8, tol_rel_b=1e-6,
+                                          disp=trust_region_options.get('disp', False)
+                                          ),
+                                      **trust_region_options)