# MatMPIAdjCreateNonemptySubcommMat
create the same `MATMPIADJ` matrix on a subcommunicator containing only processes owning a positive number of rows 
## Synopsis
```
#include "petscmat.h" 
PetscErrorCode MatMPIAdjCreateNonemptySubcommMat(Mat A, Mat *B)
```
Collective


## Input Parameter

- ***A -*** original MPIAdj matrix



## Output Parameter

- ***B -*** matrix on subcommunicator, NULL on ranks that owned zero rows of A





## Note
This function is mostly useful for internal use by mesh partitioning packages that require that every process owns at least one row.

The matrix B should be destroyed with `MatDestroy()`. The arrays are not copied, so B should be destroyed before A is destroyed.


## See Also
 `MATMPIADJ`, `MatCreateMPIAdj()`

## Level
developer

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/adj/mpi/mpiadj.c.html#MatMPIAdjCreateNonemptySubcommMat">src/mat/impls/adj/mpi/mpiadj.c</A>

## Implementations

<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/adj/mpi/mpiadj.c.html#MatMPIAdjCreateNonemptySubcommMat_MPIAdj">MatMPIAdjCreateNonemptySubcommMat_MPIAdj in src/mat/impls/adj/mpi/mpiadj.c</A><BR>


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


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