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 #ifndef __STCG 15 #define __STCG 16 17 typedef struct { 18 PetscReal radius; 19 PetscReal norm_d; 20 PetscReal o_fcn; 21 PetscInt dtype; 22 } KSP_STCG; 23 24 #endif 25 26