petsc-3.7.3 2016-08-01

MatInterpolateAdd

w = y + A*x or A'*x depending on the shape of the matrix

#include "petscmat.h" 
PetscErrorCode MatInterpolateAdd(Mat A,Vec x,Vec y,Vec w)

Neighbor-wise Collective on Mat

w may be the same vector as y.

This allows one to use either the restriction or interpolation (its transpose) matrix to do the interpolation