ISIntersect#

Computes the intersection of two index sets, by sorting and comparing.

Synopsis#

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

Collective

Input Parameters#

  • is1 - first index set

  • is2 - second index set

Output Parameter#

  • 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

is1 and is2 do not need to be sorted.

The operations are performed separately on each MPI rank

See Also#

Low-level Vector Communication, IS, ISDestroy(), ISView(), ISDifference(), ISSum(), ISExpand(), ISConcatenate()

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