petsc-3.14.6 2021-03-30

ISInvertPermutation

Creates a new permutation that is the inverse of a given permutation.

#include "petscis.h" 
PetscErrorCode  ISInvertPermutation(IS is,PetscInt nlocal,IS *isout)

Collective on IS

	is	- the index set
	nlocal	- number of indices on this processor in result (ignored for 1 proccessor) or use PETSC_DECIDE

isout

- the inverse permutation

For parallel index sets this does the complete parallel permutation, but the code is not efficient for huge index sets (10,000,000 indices).

intermediate