petsc-3.13.6 2020-09-29

ISSortPermutation

calculate the permutation of the indices into a nondecreasing order.

Synopsis

#include "petscis.h"  
PetscErrorCode ISSortPermutation(IS f,PetscBool always,IS *h)

Not collective.

Input arguments

	f	- IS to sort
	always	- build the permutation even when f's indices are nondecreasing.

Output argument

h -permutation or NULL, if f is nondecreasing and always == PETSC_FALSE.

Note: Indices in f are unchanged. f[h[i]] is the i-th smallest f index. If always == PETSC_FALSE, an extra check is peformed to see whether the f indices are nondecreasing. h is built on PETSC_COMM_SELF, since the permutation has a local meaning only.

Level

advanced

Location