# DMPlexComputeInterpolatorNested
Form the local portion of the interpolation matrix I from the coarse `DM` to a uniformly refined `DM`. 
## Synopsis
```
#include "petscdmplex.h"   
PetscErrorCode DMPlexComputeInterpolatorNested(DM dmc, DM dmf, PetscBool isRefined, Mat In, void *user)
```

## Input Parameters

- ***dmc  -*** The coarse mesh
- ***dmf  -*** The fine mesh
- ***isRefined -*** Flag indicating regular refinement, rather than the same topology
- ***user -*** The user context



## Output Parameter

- ***In  -*** The interpolation matrix





## See Also
 [](chapter_unstructured), `DM`, `DMPLEX`, `DMPlexComputeInterpolatorGeneral()`, `DMPlexComputeJacobianFEM()`

## Level
developer

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/impls/plex/plexfem.c.html#DMPlexComputeInterpolatorNested">src/dm/impls/plex/plexfem.c</A>


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


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