Hi, I'm new to PETSc, so that this can be a very simple question: I'm looking for something like VecGetSubVector, which I've seen it exists in the dev version but not in the released one. I need to write a smoother for a multigrid algorithm (something like a block Gauss Seidel) which can be written in matlab as for j = 1:ny P = <some matrix indices as function of j>; du(P) = L(P,P) \ ( rhs(P) - L(P,:)*du + D2(P,P)*du(P) ); end where L is a matrix (in my case the linearized Navier Stokes). I was thinking about using IS for declaring P, so that D2(P,P) can be obtained using MatGetSubMatrix. I would need the same for the vector du. Is there a way to do that without using the developer version? (I really don't feel like being "experienced with building, using and debugging PETSc). Thanks in advance Gianluca