petsc-3.11.2 2019-05-18
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ISIntersect

Computes the union of two index sets, by concatenating 2 lists, sorting, and finding duplicates.

Synopsis

#include "petscis.h"  
PetscErrorCode ISIntersect(IS is1,IS is2,IS *isout)
Collective on IS

Input Parameter

is1 - first index set
is2 - second index set

Output Parameters

isout -the sorted intersection of is1 and is2

Notes

Negative values are removed from the lists. This requires O(min(is1,is2)) memory and O(max(is1,is2)log(max(is1,is2))) work

The IS's do not need to be sorted.

See Also

ISDestroy(), ISView(), ISDifference(), ISSum(), ISExpand()

Level

intermediate

Location

src/vec/is/is/utils/isdiff.c
Index of all IS routines
Table of Contents for all manual pages
Index of all manual pages