PETSc version 3.17.5
PCSPAISetBlockSize
set the block size for the SPAI preconditioner
Synopsis
#include "petscpc.h"
PetscErrorCode PCSPAISetBlockSize(PC pc,int block_size1)
Input Parameters
| pc | - the preconditioner
|
| n | - block size (default 1)
|
Notes
A block
size of 1 treats A as a matrix of scalar elements. A
block size of s > 1 treats A as a matrix of sxs
blocks. A block size of 0 treats A as a matrix with
variable sized blocks, which are determined by
searching for dense square diagonal blocks in A.
This can be very effective for finite-element
matrices.
SPAI will convert A to block form, use a block
version of the preconditioner algorithm, and then
convert the result back to scalar form.
In many cases the a block-size parameter other than 1
can lead to very significant improvement in
performance.
See Also
PCSPAI, PCSetType()
Level
intermediate
Location
src/ksp/pc/impls/spai/ispai.c
Implementations
PCSPAISetBlockSize_SPAI in src/ksp/pc/impls/spai/ispai.c
Index of all PC routines
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