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 */ 13 14 #pragma once 15 16 #include <petsc/private/kspimpl.h> 17 18 typedef struct { 19 PetscReal radius; 20 PetscReal norm_d; 21 PetscReal o_fcn; 22 PetscInt dtype; 23 } KSPCG_STCG; 24