[petsc-users] VecGetSubVector

[Gianluca Meneghello]

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