**petsc-master 2017-12-13**

# 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 on PC

### Input Parameters

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

Index of all PC routines

Table of Contents for all manual pages

Index of all manual pages