dolfin team mailing list archive

[Jed Brown <jed@xxxxxxxx>]

On Wed 2008-08-13 18:31, kent-and@xxxxxxxxx wrote:
> 
> > Kent-Andre Mardal wrote:
> >> BTW: the Assembler code that computes A, b and enforces BC
> >> simultaneously in a symmetric way,
> >
> > Very nice. We can now implement some symmetric linear solvers.
> >
> > Do you keep the 'Dirichlet' dofs and zero the row and column, or do you
> > eliminate them from the global system?
> 
> The Dirichlet dofs are kept. I thought that was simplest to do..

It is certainly more work at this stage, but there are significant
benefits to actually removing the degrees of freedom.  In particular, it
allows more preconditioners to be effective and makes related matrices
(i.e. the Schur complement) better conditioned.

Jed

Attachment: pgprajTWUH5cG.pgp
Description: PGP signature