[petsc-dev] Bordered systems and low-rank corrections

[Mark F. Adams]

Uzawa is an iterative method on the the Schur complement matrix,  You can do preconditioned Uzawa which needs a preconditioner for the Schur compliment.  And I was referring the Woodbury page.

FYI: the yellow SIAM book on mixed FE methods by Brezi and Fortin has an excellent 2 page section on Uzawa that give, among other things, a precise recipe for Uzawa (page 99 I think) including preconditioning and a non-zero RHS for the constraint part.

On Nov 4, 2011, at 9:45 PM, Jed Brown wrote:

> On Fri, Nov 4, 2011 at 13:55, Mark F. Adams <mark.adams at columbia.edu> wrote:
> The two actually look very similar.  The community that I learned Uzawa from is very familiar with Sherman-Morrison.   Uzawa might in fact be an iterative S-M ... the wikapedia page does not explain how to recover the solution Y and does not accommodate a non-zero RHS for the constraint equations.  Both of which you'd want to do to be general.
> 
> Well, the Schur complement is in the other direction. Are you talking about the Uzawa or Sherman-Morrison page? It's easy enough either way.

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-dev/attachments/20111105/06f8518e/attachment.html>