:orphan:
# MatMPIAIJGetLocalMat
Creates a `MATSEQAIJ` 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
In other words combines the two parts of a parallel `MATMPIAIJ` matrix on each process to a single matrix.

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
 [](ch_matrices), `Mat`, `MATMPIAIJ`, `MatGetOwnershipRange()`, `MatMPIAIJGetLocalMatCondensed()`, `MatMPIAIJGetLocalMatMerge()`

## Level
developer

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/aij/mpi/mpiaij.c.html#MatMPIAIJGetLocalMat">src/mat/impls/aij/mpi/mpiaij.c</A>


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[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/mat/impls/aij/mpi/mpiaij.c)


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