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# PCBDDCSetCoarseningRatio
Set coarsening ratio used in the multi-level version of `PCBDDC` 
## Synopsis
```
#include "petscpc.h" 
PetscErrorCode PCBDDCSetCoarseningRatio(PC pc, PetscInt k)
```
Logically Collective


## Input Parameters

- ***pc -*** the preconditioning context
- ***k -*** coarsening ratio (H/h at the coarser level)



## Options Database Key

- ***-pc_bddc_coarsening_ratio <int> -*** Set the coarsening ratio used in multi-level coarsening





## Note
Approximately `k` subdomains at the finer level will be aggregated into a single subdomain at the coarser level


## See Also
 `PCBDDC`, `PCBDDCSetLevels()`

## Level
intermediate

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

## Implementations

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


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


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