ISGetPointRange#
Returns a description of the points in an IS suitable for traversal
Synopsis#
#include "petscis.h"
PetscErrorCode ISGetPointRange(IS pointIS, PetscInt *pStart, PetscInt *pEnd, const PetscInt *points[])
Not Collective
Input Parameter#
pointIS - The
ISobject
Output Parameters#
pStart - The first index, see notes
pEnd - One past the last index, see notes
points - The indices, see notes
Notes#
If the IS contains contiguous indices in an ISSTRIDE, then the indices are contained in [pStart, pEnd) and points = NULL.
Otherwise, pStart = 0, pEnd = numIndices, and points is an array of the indices. This supports the following pattern
ISGetPointRange(is, &pStart, &pEnd, &points);
for (p = pStart; p < pEnd; ++p) {
const PetscInt point = points ? points[p] : p;
// use point
}
ISRestorePointRange(is, &pstart, &pEnd, &points);
Hence the same code can be written for pointIS being a ISSTRIDE or ISGENERAL
See Also#
Low-level Vector Communication, IS, ISRestorePointRange(), ISGetPointSubrange(), ISGetIndices(), ISCreateStride()
Level#
intermediate
Location#
Index of all IS routines
Table of Contents for all manual pages
Index of all manual pages