On Mon, Jan 9, 2012 at 22:47, Mohamad M. Nasr-Azadani <mmnasr at gmail.com>wrote:
> It might be a naive question, but I am wondering how KSPSetNullSpace() > works when it is passed to a linear system ksp context? > Say, for instance, we have the simple case of Poisson equation solved in a > square domain and Neumann boundary condition applied to all boundaries. > Does it take the integral of the solution and set it to zero as an extra > constraint? > It just projects out whatever you provide as a null space, so the Krylov method effectively runs in the remaining subspace. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20120109/9d087558/attachment.htm>
