1: /*
  2:     Context for conjugate gradient method (unconstrained minimization)
  3:  */

  5: #pragma once

  7: #include <petsc/private/taoimpl.h>

  9: typedef struct {
 10:   Vec G_old;
 11:   Vec X_old;
 12:   Vec W; /*  work vector */

 14:   PetscReal eta;       /*  Restart tolerance */
 15:   PetscReal delta_max; /*  Minimum value for scaling */
 16:   PetscReal delta_min; /*  Maximum value for scaling */

 18:   /*  The algorithm restarts when the gradient at the current point g_k,
 19:        and the gradient of the previous point, g_{k-1}, satisfy the
 20:        following inequality:

 22:             abs(inner(g_k, g_{k-1})) > eta * norm(g_k, 2)^2. */

 24:   PetscInt ngradsteps;  /*  Number of gradient steps */
 25:   PetscInt nresetsteps; /*  Number of reset steps */

 27:   PetscInt cg_type; /*  Formula to use */
 28: } TAO_CG;