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: /*****************************************************************************/
17: typedef struct {
18: PetscReal radius;
19: PetscReal norm_d;
20: PetscReal o_fcn;
21: PetscInt dtype;
22: } KSP_STCG;
24: #endif