On May 25, 2012, at 8:59 AM, Jed Brown wrote: > On Fri, May 25, 2012 at 1:07 AM, Mark F. Adams <mark.adams at columbia.edu> > wrote: > And, I've never seen Gauss-Siedel used with Cheby because G-S has the correct > damping properties, as is, for the Laplacian. > > The point is to have something adequate for things that are not Laplacians. I > tried running SOR without Cheby, but it was far less robust. > > So I know it looks funny, but I don't have a similarly robust alternative. If > we are living in a world where local work is cheap, we might as well do local > SOR instead of pbjacobi. (Note that Cheby+pbjacobi is nearly as good as > Cheby+SOR in some cases, but much worse in others.) > > > Note, G-S is not symmetric and Cheby for unsymmetric is a different can of > worms. So if A is symmetric then maybe try SSOR. > > The default SOR is local_symmetric.
So it does a forward and backward pass. So it is really two smoothing steps. One should compare it with two additive smoothers. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-dev/attachments/20120525/5996b3ea/attachment.html>
