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# PCHMGSetUseSubspaceCoarsening
Use subspace coarsening in `PCHMG` 
## Synopsis
```
#include "petscpc.h" 
PetscErrorCode PCHMGSetUseSubspaceCoarsening(PC pc, PetscBool subspace)
```
Logically Collective


## Input Parameters

- ***pc -*** the `PCHMG` context
- ***reuse -*** `PETSC_TRUE` indicates that `PCHMG` will use the subspace coarsening



## Options Database Key

- ***-pc_hmg_use_subspace_coarsening  <true | false> -*** Whether or not to use subspace coarsening (that is, coarsen a submatrix).





## See Also
 `PCHMG`, `PCHMGSetReuseInterpolation()`, `PCHMGSetCoarseningComponent()`, `PCHMGSetInnerPCType()`

## Level
beginner

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/pc/impls/hmg/hmg.c.html#PCHMGSetUseSubspaceCoarsening">src/ksp/pc/impls/hmg/hmg.c</A>

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

## Implementations

<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/pc/impls/hmg/hmg.c.html#PCHMGSetUseSubspaceCoarsening_HMG">PCHMGSetUseSubspaceCoarsening_HMG in src/ksp/pc/impls/hmg/hmg.c</A><BR>


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[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/ksp/pc/impls/hmg/hmg.c)


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