:orphan:
# PCExoticSetType
Sets the type of coarse grid interpolation to use
## Synopsis
```
#include "petscdmda.h"
#include "petscksp.h"
PetscErrorCode PCExoticSetType(PC pc, PCExoticType type)
```
Logically Collective
## Input Parameters
- ***pc -*** the preconditioner context
- ***type -*** either PC_EXOTIC_FACE or PC_EXOTIC_WIREBASKET (defaults to face)
## Notes
The face based interpolation has 1 degree of freedom per face and ignores the
edge and vertex values completely in the coarse problem. For any seven point
stencil the interpolation of a constant on all faces into the interior is that constant.
The wirebasket interpolation has 1 degree of freedom per vertex, per edge and
per face. A constant on the subdomain boundary is interpolated as that constant
in the interior of the domain.
The coarse grid matrix is obtained via the Galerkin computation A_c = R A R^T, hence
if A is nonsingular A_c is also nonsingular.
Both interpolations are suitable for only scalar problems.
## See Also
`PCEXOTIC`, `PCExoticType()`
## Level
intermediate
## Location
src/ksp/pc/impls/wb/wb.c
## Implementations
PCExoticSetType_Exotic in src/ksp/pc/impls/wb/wb.c
---
[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/ksp/pc/impls/wb/wb.c)
[Index of all PC routines](index.md)
[Table of Contents for all manual pages](/manualpages/index.md)
[Index of all manual pages](/manualpages/singleindex.md)