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# MatGetLocalSize
For most matrix formats, excluding `MATELEMENTAL` and `MATSCALAPACK`, Returns the number of local rows and local columns of a matrix. For all matrices this is the local size of the left and right vectors as returned by `MatCreateVecs()`. 
## Synopsis
```
#include "petscmat.h" 
PetscErrorCode MatGetLocalSize(Mat mat, PetscInt *m, PetscInt *n)
```
Not Collective


## Input Parameter

- ***mat -*** the matrix



## Output Parameters

- ***m -*** the number of local rows, use `NULL` to not obtain this value
- ***n -*** the number of local columns, use `NULL` to not obtain this value





## See Also
 [](ch_matrices), `Mat`, `MatSetSizes()`, `MatGetSize()`

## Level
beginner

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/interface/matrix.c.html#MatGetLocalSize">src/mat/interface/matrix.c</A>

## Examples
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/ksp/tutorials/ex10.c.html">src/ksp/ksp/tutorials/ex10.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/ksp/tutorials/ex27.c.html">src/ksp/ksp/tutorials/ex27.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/ksp/tutorials/ex72.c.html">src/ksp/ksp/tutorials/ex72.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/ksp/tutorials/ex77.c.html">src/ksp/ksp/tutorials/ex77.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/ksp/tutorials/ex77f.F90.html">src/ksp/ksp/tutorials/ex77f.F90</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/snes/tutorials/ex12.c.html">src/snes/tutorials/ex12.c</A><BR>


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[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/mat/interface/matrix.c)


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