petsc-3.13.6 2020-09-29

VecGetValues

Gets values from certain locations of a vector. Currently can only get values on the same processor

#include "petscvec.h"   
PetscErrorCode  VecGetValues(Vec x,PetscInt ni,const PetscInt ix[],PetscScalar y[])

Not Collective

	x	- vector to get values from
	ni	- number of elements to get
	ix	- indices where to get them from (in global 1d numbering)

y -array of values

The user provides the allocated array y; it is NOT allocated in this routine

VecGetValues() gets y[i] = x[ix[i]], for i=0,...,ni-1.

VecAssemblyBegin() and VecAssemblyEnd() MUST be called before calling this

VecGetValues() uses 0-based indices in Fortran as well as in C.

If you call VecSetOption(x, VEC_IGNORE_NEGATIVE_INDICES,PETSC_TRUE), negative indices may be passed in ix. These rows are simply ignored.

beginner