petsc-3.14.6 2021-03-30

ISComplement

Given an index set (IS) generates the complement index set. That is all all indices that are NOT in the given set.

#include "petscis.h"  
PetscErrorCode  ISComplement(IS is,PetscInt nmin,PetscInt nmax,IS *isout)

Collective on IS

	is	- the index set
	nmin	- the first index desired in the local part of the complement
	nmax	- the largest index desired in the local part of the complement (note that all indices in is must be greater or equal to nmin and less than nmax)

isout

- the complement

The communicator for this new IS is the same as for the input IS

For a parallel IS, this will generate the local part of the complement on each process

To generate the entire complement (on each process) of a parallel IS, first call ISAllGather() and then call this routine.

intermediate