1: /*****************************************************************************/
  2: /* Context for using preconditioned conjugate gradient method to minimized a */
  3: /* quadratic function subject to a trust region constraint.  If the matrix   */
  4: /* is indefinite, a direction of negative curvature may be encountered.  If  */
  5: /* a direction of negative curvature is found, then we follow it to the      */
  6: /* boundary of the trust region.                                             */
  7: /*                                                                           */
  8: /* This method is described in:                                              */
  9: /*   T. Steihaug, "The Conjugate Gradient Method and Trust Regions in Large  */
 10: /*     Scale Optimization", SIAM Journal on Numerical Analysis, 20,          */
 11: /*     pages 626-637, 1983.                                                  */
 12: /*****************************************************************************/

 14: #pragma once

 16: #include <petsc/private/kspimpl.h>

 18: typedef struct {
 19:   PetscReal radius;
 20:   PetscReal norm_d;
 21:   PetscReal o_fcn;
 22:   PetscInt  dtype;
 23: } KSPCG_STCG;