PCGalerkinSetComputeSubmatrix#
Provide a routine that will be called to compute the Galerkin submatrix
Synopsis#
#include "petscksp.h"
PetscErrorCode PCGalerkinSetComputeSubmatrix(PC pc, PetscErrorCode (*computeAsub)(PC pc, Mat A, Mat Ap, Mat *cAp, void *ctx), void *ctx)
Logically Collective
Input Parameters#
pc - the preconditioner context
computeAsub - routine that computes the submatrix from the global matrix
ctx - context used by the routine, or
NULL
Calling sequence of computeAsub
#
pc - the
PCGALERKIN
preconditionerA - the matrix in the
PCGALERKIN
Ap - the computed submatrix from any previous computation, if
NULL
it has not previously been computedcAp - the submatrix computed by this routine
ctx - optional user-defined function context
Notes#
Instead of providing this routine you can call PCGalerkinGetKSP()
and then KSPSetOperators()
to provide the submatrix,
but that will not work for multiple KSPSolve()
s with different matrices unless you call it for each solve.
This routine is called each time the outer matrix is changed. In the first call the Ap argument is NULL
and the routine should create the
matrix and computes its values in cAp. On each subsequent call the routine should up the Ap matrix.
Developer Notes#
If the user does not call this routine nor call PCGalerkinGetKSP()
and KSPSetOperators()
then PCGALERKIN
could automatically compute the submatrix via calls to MatGalerkin()
or MatRARt()
See Also#
KSP: Linear System Solvers, PC
, PCCreate()
, PCSetType()
, PCType
, PCGALERKIN
,
PCGalerkinSetRestriction()
, PCGalerkinSetInterpolation()
, PCGalerkinGetKSP()
Level#
intermediate
Location#
Implementations#
Index of all PC routines
Table of Contents for all manual pages
Index of all manual pages