MatCreateSeqBAIJ

Creates a sparse matrix in block AIJ (block compressed row) format. For good matrix assembly performance the user should preallocate the matrix storage by setting the parameter nz (or the array nnz). By setting these parameters accurately, performance during matrix assembly can be increased by more than a factor of 50.

Synopsis

#include "petscmat.h" 
int MatCreateSeqBAIJ(MPI_Comm comm,int bs,int m,int n,int nz,int *nnz,Mat *A)

Collective on MPI_Comm

Input Parameters

	comm	- MPI communicator, set to PETSC_COMM_SELF
	bs	- size of block
	m	- number of rows
	n	- number of columns
	nz	- number of nonzero blocks per block row (same for all rows)
	nnz	- array containing the number of nonzero blocks in the various block rows (possibly different for each block row) or PETSC_NULL

Output Parameter

A -the matrix

Options Database Keys

-mat_no_unroll -uses code that does not unroll the loops in the block calculations (much slower)

-mat_block_size -size of the blocks to use

Notes

A nonzero block is any block that as 1 or more nonzeros in it

The block AIJ format is fully compatible with standard Fortran 77 storage. That is, the stored row and column indices can begin at either one (as in Fortran) or zero. See the users' manual for details.

Specify the preallocated storage with either nz or nnz (not both). Set nz=PETSC_DEFAULT and nnz=PETSC_NULL for PETSc to control dynamic memory allocation. For additional details, see the users manual chapter on matrices.

Examples

src/sles/examples/tutorials/ex1.c.html