petsc-3.14.5 2021-03-03
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# MatMPIAIJGetLocalMat

Creates a SeqAIJ from a MATMPIAIJ matrix by taking all its local rows and putting them into a sequential matrix with mlocal rows and n columns. Where mlocal is the row count obtained with MatGetLocalSize() and n is the global column count obtained with MatGetSize()

### Synopsis

    #include "petscmat.h"
    PetscErrorCode MatMPIAIJGetLocalMat(Mat A,MatReuse scall,Mat *A_loc)

Not Collective

### Input Parameters

| A | - the matrix
| scall | - either MAT_INITIAL_MATRIX or MAT_REUSE_MATRIX

### Output Parameter

| A_loc | - the local sequential matrix generated

### Notes

When the communicator associated with A has size 1 and MAT_INITIAL_MATRIX is requested, the matrix returned is the diagonal part of A. If MAT_REUSE_MATRIX is requested with comm size 1, MatCopy(Adiag,*A_loc,SAME_NONZERO_PATTERN) is called. This means that one can preallocate the proper sequential matrix first and then call this routine with MAT_REUSE_MATRIX to safely modify the values of the returned A_loc.

### See Also

MatGetOwnershipRange(), MatMPIAIJGetLocalMatCondensed()

### Level

developer

### Location

src/mat/impls/aij/mpi/mpiaij.c
Index of all Mat routines
Table of Contents for all manual pages
Index of all manual pages