:orphan:
# DMFindRegionNum
Find the region number for a given `PetscDS`, or -1 if it is not found. 
## Synopsis
```
#include "petscdm.h"          
#include "petscdmlabel.h"     
#include "petscds.h"     
PetscErrorCode DMFindRegionNum(DM dm, PetscDS ds, PetscInt *num)
```
Not Collective


## Input Parameters

- ***dm  -*** The `DM`
- ***ds  -*** The `PetscDS` defined on the given region



## Output Parameter

- ***num -*** The region number, in [0, Nds), or -1 if not found





## See Also
 [](ch_dmbase), `DM`, `DMGetRegionNumDS()`, `DMGetRegionDS()`, `DMSetRegionDS()`, `DMGetDS()`, `DMGetCellDS()`

## Level
advanced

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/interface/dm.c.html#DMFindRegionNum">src/dm/interface/dm.c</A>


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


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