[petsc-dev] Multigrid is confusing

[Jed Brown]

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.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-dev/attachments/20120525/7564f969/attachment.html>