:orphan:
# DMCoarsen
Coarsens a `DM` object using a standard, non-adaptive coarsening of the underlying mesh 
## Synopsis
```
#include "petscdm.h"          
#include "petscdmlabel.h"     
#include "petscds.h"     
PetscErrorCode DMCoarsen(DM dm, MPI_Comm comm, DM *dmc)
```
Collective


## Input Parameters

- ***dm -*** the `DM` object
- ***comm -*** the communicator to contain the new `DM` object (or `MPI_COMM_NULL`)



## Output Parameter

- ***dmc -*** the coarsened `DM`





## See Also
 [](ch_dmbase), `DM`, `DMRefine()`, `DMDestroy()`, `DMView()`, `DMCreateGlobalVector()`, `DMCreateInterpolation()`

## Level
developer

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

## Examples
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/impls/stag/tutorials/ex4.c.html">src/dm/impls/stag/tutorials/ex4.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/ksp/tutorials/ex65.c.html">src/ksp/ksp/tutorials/ex65.c</A><BR>

## Implementations

<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/impls/composite/pack.c.html#DMCoarsen_Composite">DMCoarsen_Composite in src/dm/impls/composite/pack.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/impls/da/da.c.html#DMCoarsen_DA">DMCoarsen_DA in src/dm/impls/da/da.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/impls/forest/forest.c.html#DMCoarsen_Forest">DMCoarsen_Forest in src/dm/impls/forest/forest.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/impls/moab/dmmbmg.cxx.html#DMCoarsen_Moab">DMCoarsen_Moab in src/dm/impls/moab/dmmbmg.cxx</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/impls/plex/plexcoarsen.c.html#DMCoarsen_Plex">DMCoarsen_Plex in src/dm/impls/plex/plexcoarsen.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/impls/redundant/dmredundant.c.html#DMCoarsen_Redundant">DMCoarsen_Redundant in src/dm/impls/redundant/dmredundant.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/impls/stag/stag.c.html#DMCoarsen_Stag">DMCoarsen_Stag in src/dm/impls/stag/stag.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/snes/impls/vi/rs/virs.c.html#DMCoarsen_SNESVI">DMCoarsen_SNESVI in src/snes/impls/vi/rs/virs.c</A><BR>


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


[Index of all DM routines](index.md)  
[Table of Contents for all manual pages](/manualpages/index.md)  
[Index of all manual pages](/manualpages/singleindex.md)