PCModifySubMatrices#
Calls an optional user-defined routine within certain preconditioners if one has been set with PCSetModifySubMatrices().
Synopsis#
#include "petscksp.h"
PetscErrorCode PCModifySubMatrices(PC pc, PetscInt nsub, const IS row[], const IS col[], Mat submat[], void *ctx)
Collective
Input Parameters#
pc - the preconditioner context
nsub - the number of local submatrices
row - an array of index sets that contain the global row numbers that comprise each local submatrix
col - an array of index sets that contain the global column numbers that comprise each local submatrix
submat - array of local submatrices
ctx - optional user-defined context for private data for the user-defined routine (may be null)
Output Parameter#
submat - array of local submatrices (the entries of which may have been modified)
Notes#
The user should NOT generally call this routine, as it will automatically be called within certain preconditioners (currently block Jacobi, additive Schwarz) if set.
The basic submatrices are extracted from the preconditioner matrix as usual; the user can then alter these (for example, to set different boundary conditions for each submatrix) before they are used for the local solves.
See Also#
Level#
developer
Location#
Index of all PC routines
Table of Contents for all manual pages
Index of all manual pages