VecGetSubVector#

Gets a vector representing part of another vector

Synopsis#

#include "petscvec.h"   
PetscErrorCode VecGetSubVector(Vec X, IS is, Vec *Y)

Collective

Input Parameters#

X - vector from which to extract a subvector
is - index set representing portion of X to extract

Output Parameter#

Y - subvector corresponding to is

Notes#

The subvector Y should be returned with VecRestoreSubVector(). X and is must be defined on the same communicator

Changes to the subvector will be reflected in the X vector on the call to VecRestoreSubVector().

This function may return a subvector without making a copy, therefore it is not safe to use the original vector while modifying the subvector. Other non-overlapping subvectors can still be obtained from X using this function.

The resulting subvector inherits the block size from is if greater than one. Otherwise, the block size is guessed from the block size of the original X.