PCGASMCreateSubdomains#

Creates n index sets defining n nonoverlapping subdomains on this MPI process for the PCGASM additive Schwarz preconditioner for a any problem based on its matrix.

Synopsis#

#include "petscpc.h" 
PetscErrorCode PCGASMCreateSubdomains(Mat A, PetscInt N, PetscInt *n, IS *iis[])

Collective

Input Parameters#

A - The global matrix operator
N - the number of global subdomains requested

Output Parameters#

n - the number of subdomains created on this MPI rank
iis - the array of index sets defining the local inner subdomains (on which the correction is applied)

Notes#

When N >= A’s communicator size, each subdomain is local – contained within a single MPI process. When N < size, the subdomains are ‘straddling’ (rank boundaries) and are no longer local. The resulting subdomains can be use in PCGASMSetSubdomains(pc,n,iss,NULL). The overlapping outer subdomains will be automatically generated from these according to the requested amount of overlap; this is currently supported only with local subdomains.

Use PCGASMDestroySubdomains() to free the array and the list of index sets.