1 /* 2 Context for conjugate gradient method (unconstrained minimization) 3 */ 4 5 #ifndef __TAO_CG_H 6 #define __TAO_CG_H 7 8 #include <petsc/private/taoimpl.h> 9 10 typedef struct { 11 Vec G_old; 12 Vec X_old; 13 Vec W; /* work vector */ 14 15 PetscReal eta; /* Restart tolerance */ 16 PetscReal delta_max; /* Minimum value for scaling */ 17 PetscReal delta_min; /* Maximum value for scaling */ 18 19 /* The algorithm restarts when the gradient at the current point g_k, 20 and the gradient of the previous point, g_{k-1}, satisfy the 21 following inequality: 22 23 abs(inner(g_k, g_{k-1})) > eta * norm(g_k, 2)^2. */ 24 25 PetscInt ngradsteps; /* Number of gradient steps */ 26 PetscInt nresetsteps; /* Number of reset steps */ 27 28 PetscInt cg_type; /* Formula to use */ 29 } TAO_CG; 30 31 #endif /* ifndef __TAO_CG_H */ 32