MatMPIAIJSetPreallocationCSR#
Allocates memory for a sparse parallel matrix in MATAIJ format (the default parallel PETSc format).
Synopsis#
#include "petscmat.h"
PetscErrorCode MatMPIAIJSetPreallocationCSR(Mat B, const PetscInt i[], const PetscInt j[], const PetscScalar v[])
Collective
Input Parameters#
B - the matrix
i - the indices into
jfor the start of each local row (indices start with zero)j - the column indices for each local row (indices start with zero)
v - optional values in the matrix
Notes#
The i, j, and v 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 v 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.
A convenience routine for this functionality is MatCreateMPIAIJWithArrays().
You can update the matrix with new numerical values using MatUpdateMPIAIJWithArrays() after this call if the column indices in j are sorted.
If you do not use MatUpdateMPIAIJWithArrays(), the column indices in j do not need to be sorted. If you will use
MatUpdateMPIAIJWithArrays(), the column indices must be sorted.
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 = 3]
v = {1,2,3} [size = 3]
Process1 [P1] rows_owned=[2]
i = {0,3} [size = nrow+1 = 1+1]
j = {0,1,2} [size = 3]
v = {4,5,6} [size = 3]
See Also#
Matrices, Mat, MATMPIAIJ, MatCreate(), MatCreateSeqAIJ(), MatSetValues(), MatMPIAIJSetPreallocation(), MatCreateAIJ(),
MatCreateSeqAIJWithArrays(), MatCreateMPIAIJWithSplitArrays(), MatCreateMPIAIJWithArrays(), MatSetPreallocationCOO(), MatSetValuesCOO()
Level#
developer
Location#
Implementations#
MatMPIAIJSetPreallocationCSR_MPIAIJ() in src/mat/impls/aij/mpi/mpiaij.c
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