petsc-3.6.2 2015-10-02
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# PCGASMSetSubdomains

Sets the subdomains for this processor for the additive Schwarz preconditioner.

### Synopsis

    #include "petscpc.h"
    PetscErrorCode  PCGASMSetSubdomains(PC pc,PetscInt n,IS iis[],IS ois[])

Collective on pc

### Input Parameters

| pc | - the preconditioner object
| n | - the number of subdomains for this processor
| iis | - the index sets that define the inner subdomains (or NULL for PETSc to determine subdomains)
| ois | - the index sets that define the outer subdomains (or NULL to use the same as iis, or to construct by expanding iis by the requested overlap)

### Notes

The IS indices use the parallel, global numbering of the vector entries. Inner subdomains are those where the correction is applied. Outer subdomains are those where the residual necessary to obtain the corrections is obtained (see PCGASMType for the use of inner/outer subdomains). Both inner and outer subdomains can extend over several processors. This processor's portion of a subdomain is known as a local subdomain.

By default the GASM preconditioner uses 1 (local) subdomain per processor.

### Keywords

PC, GASM, set, subdomains, additive Schwarz

### See Also

PCGASMSetNumSubdomains(), PCGASMSetOverlap(), PCGASMGetSubKSP(),
PCGASMCreateSubdomains2D(), PCGASMGetSubdomains()

Level:advanced
Location: src/ksp/pc/impls/gasm/gasm.c
Index of all PC routines
Table of Contents for all manual pages
Index of all manual pages

### Examples

src/ksp/ksp/examples/tutorials/ex62.c.html