#include "tao.h" int TaoAppSetHessianRoutine(TAO_APPLICATION taoapp, int (*hess)(TAO_APPLICATION,Vec,Mat*,Mat*,MatStructure*,void*),void *ctx)Collective on TAO_APPLICATION and Mat
taoapp | - the TAO_APPLICATION context | |
hess | - Hessian evaluation routine | |
ctx | - [optional] user-defined context for private data for the Hessian evaluation routine (may be TAO_NULL) |
hess (TAO_APPLICATION taoapp,Vec x,Mat *H,Mat *Hpre,int *flag,void *ctx);
taoapp | - the TAO_APPLICATION context | |
x | - input vector | |
H | - Hessian matrix | |
Hpre | - preconditioner matrix, usually the same as A | |
flag | - flag indicating information about the preconditioner matrix structure (see below) | |
ctx | - [optional] user-defined Hessian context |
The function hess() takes Mat * as the matrix arguments rather than Mat. This allows the Hessian evaluation routine to replace A and/or B with a completely new new matrix structure (not just different matrix elements) when appropriate, for instance, if the nonzero structure is changing throughout the global iterations.
The flag can be used to eliminate unnecessary work in the preconditioner during the repeated solution of linear systems of the same size. The available options are
SAME_PRECONDITIONER -
B is identical during successive linear solves.
This option is intended for folks who are using
different Amat and Pmat matrices and want to reuse the
same preconditioner matrix. For example, this option
saves work by not recomputing incomplete factorization
for ILU/ICC preconditioners.
SAME_NONZERO_PATTERN -
B has the same nonzero structure during
successive linear solves.
DIFFERENT_NONZERO_PATTERN -
B does not have the same nonzero structure.
If in doubt about whether your preconditioner matrix has changed structure or not, use the flag DIFFERENT_NONZERO_PATTERN.
Level:beginner
Location:src/petsctao/application/petscapp/tao_app_fg.c
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