petsc-3.11.4 2019-09-28

MatCheckCompressedRow

Determines whether the compressed row matrix format should be used. If the format is to be used, this routine creates Mat_CompressedRow struct. Compressed row format provides high performance routines by taking advantage of zero rows. Supported types are MATAIJ, MATBAIJ and MATSBAIJ.

Synopsis

#include "petscmat.h"  
PETSC_EXTERN PetscErrorCode MatCheckCompressedRow(Mat A,PetscInt nrows,Mat_CompressedRow *compressedrow,PetscInt *ai,PetscInt mbs,PetscReal ratio)

Collective

Input Parameters

	A	- the matrix
	nrows	- number of rows with nonzero entries
	compressedrow	- pointer to the struct Mat_CompressedRow
	ai	- row pointer used by seqaij and seqbaij
	mbs	- number of (block) rows represented by ai
	ratio	- ratio of (num of zero rows)/m, used to determine if the compressed row format should be used

Notes

By default PETSc will not check for compressed rows on sequential matrices. Call MatSetOption(Mat,MAT_CHECK_COMPRESSED_ROW,PETSC_TRUE); before MatAssemblyBegin() to have it check.

Developer Note: The reason this takes the compressedrow, ai and mbs arguments is because it is called by both the SeqAIJ and SEQBAIJ matrices and the values are not therefore obtained by directly taking the values from the matrix object. This is not a general public routine and hence is not listed in petscmat.h (it exposes a private data structure) but it is used by some preconditioners and hence is labeled as PETSC_EXTERN

Level

developer

Location

src/mat/utils/compressedrow.c
Index of all Mat routines
Table of Contents for all manual pages
Index of all manual pages