:orphan:
# 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 `MATMPIADJ` 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
 [](ch_matrices), `Mat`, `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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