petsc-3.4.5 2014-06-29

MatCreateMPIAIJWithArrays

creates a MPI AIJ matrix using arrays that contain in standard CSR format the local rows.

Synopsis

#include "petscmat.h" 
PetscErrorCode  MatCreateMPIAIJWithArrays(MPI_Comm comm,PetscInt m,PetscInt n,PetscInt M,PetscInt N,const PetscInt i[],const PetscInt j[],const PetscScalar a[],Mat *mat)

Collective on MPI_Comm

Input Parameters

	comm	- MPI communicator
	m	- number of local rows (Cannot be PETSC_DECIDE)
	n	- This value should be the same as the local size used in creating the x vector for the matrix-vector product y = Ax. (or PETSC_DECIDE to have calculated if N is given) For square matrices n is almost always m.
	M	- number of global rows (or PETSC_DETERMINE to have calculated if m is given)
	N	- number of global columns (or PETSC_DETERMINE to have calculated if n is given)
	i	- row indices
	j	- column indices
	a	- matrix values

Output Parameter

mat -the matrix

Notes

The i, j, and a arrays ARE copied by this routine into the internal format used by PETSc; thus you CANNOT change the matrix entries by changing the values of a[] after you have called this routine. Use MatCreateMPIAIJWithSplitArrays() to avoid needing to copy the arrays.

The i and j indices are 0 based, and i indices are indices corresponding to the local j array.

The format which is used for the sparse matrix input, is equivalent to a row-major ordering.. i.e for the following matrix, the input data expected is

as shown

1 0 0 2 0 3 P0 ------- 4 5 6 P1

Process0 [P0]: rows_owned=[0,1] i = {0,1,3} [size = nrow+1 = 2+1] j = {0,0,2} [size = nz = 6] v = {1,2,3} [size = nz = 6]

Process1 [P1]: rows_owned=[2] i = {0,3} [size = nrow+1 = 1+1] j = {0,1,2} [size = nz = 6] v = {4,5,6} [size = nz = 6]

Keywords

matrix, aij, compressed row, sparse, parallel