:orphan:
# DMCreateInterpolation
Gets the interpolation matrix between two `DM` objects. The resulting matrix map degrees of freedom in the vector obtained by `DMCreateGlobalVector()` on the coarse `DM` to similar vectors on the fine grid `DM`. 
## Synopsis
```
#include "petscdm.h"          
#include "petscdmlabel.h"     
#include "petscds.h"     
PetscErrorCode DMCreateInterpolation(DM dmc, DM dmf, Mat *mat, Vec *vec)
```
Collective


## Input Parameters

- ***dmc -*** the `DM` object
- ***dmf -*** the second, finer `DM` object



## Output Parameters

- ***mat -*** the interpolation
- ***vec -*** the scaling (optional), see `DMCreateInterpolationScale()`





## Notes
For `DMDA` objects this only works for "uniform refinement", that is the refined mesh was obtained `DMRefine()` or the coarse mesh was obtained by
DMCoarsen(). The coordinates set into the `DMDA` are completely ignored in computing the interpolation.

For `DMDA` objects you can use this interpolation (more precisely the interpolation from the `DMGetCoordinateDM()`) to interpolate the mesh coordinate
vectors EXCEPT in the periodic case where it does not make sense since the coordinate vectors are not periodic.


## See Also
 [](ch_dmbase), `DM`, `DMDestroy()`, `DMView()`, `DMCreateGlobalVector()`, `DMCreateColoring()`, `DMCreateMatrix()`, `DMCreateMassMatrix()`, `DMRefine()`, `DMCoarsen()`, `DMCreateRestriction()`, `DMCreateInterpolationScale()`

## Level
developer

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/interface/dm.c.html#DMCreateInterpolation">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/dm/tutorials/ex3.c.html">src/dm/tutorials/ex3.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/ksp/tutorials/ex35.cxx.html">src/ksp/ksp/tutorials/ex35.cxx</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/ksp/tutorials/ex36.cxx.html">src/ksp/ksp/tutorials/ex36.cxx</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/ksp/tutorials/ex42.c.html">src/ksp/ksp/tutorials/ex42.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>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/ksp/tutorials/ex73.c.html">src/ksp/ksp/tutorials/ex73.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/snes/tutorials/ex36.c.html">src/snes/tutorials/ex36.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/snes/tutorials/ex48.c.html">src/snes/tutorials/ex48.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ts/tutorials/ex29.c.html">src/ts/tutorials/ex29.c</A><BR>

## Implementations

<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/impls/composite/pack.c.html#DMCreateInterpolation_Composite">DMCreateInterpolation_Composite in src/dm/impls/composite/pack.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/impls/da/dainterp.c.html#DMCreateInterpolation_DA">DMCreateInterpolation_DA in src/dm/impls/da/dainterp.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/impls/forest/p4est/pforest.h.html#DMCreateInterpolation_pforest">DMCreateInterpolation_pforest in src/dm/impls/forest/p4est/pforest.h</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/impls/moab/dmmbmg.cxx.html#DMCreateInterpolation_Moab">DMCreateInterpolation_Moab in src/dm/impls/moab/dmmbmg.cxx</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/impls/plex/plex.c.html#DMCreateInterpolation_Plex">DMCreateInterpolation_Plex in src/dm/impls/plex/plex.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/impls/redundant/dmredundant.c.html#DMCreateInterpolation_Redundant">DMCreateInterpolation_Redundant in src/dm/impls/redundant/dmredundant.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/impls/stag/stag.c.html#DMCreateInterpolation_Stag">DMCreateInterpolation_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#DMCreateInterpolation_SNESVI">DMCreateInterpolation_SNESVI in src/snes/impls/vi/rs/virs.c</A><BR>


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