On Mon, Aug 8, 2011 at 10:31 PM, Jed Brown <jedbrown at mcs.anl.gov> wrote:
> On Mon, Aug 8, 2011 at 17:16, Barry Smith <bsmith at mcs.anl.gov> wrote: > >> Add a KSP/SNES./TSSetDirichlet(ksp,snes,ts,IS listofnodes,Vec >> valuesfornodes)? >> > > This might be worthwhile. It needs a new Mat primitive which zeros the rows > and columns while also "remembering" the column values that it zeroed (as > another assembled matrix). I think it's best to apply the transformation > immediately after residuals are calculated so that norms are correct (not in > KSP at all). Matrix values are not available at this time so the Dirichlet > equations may not be scaled correctly for GMG. We have to be careful that > the residual evaluation passed to MatMFFD has the Dirichlet projection > inside it. > This is exactly the reason that I abandoned this approach when I got to nonlinear equations. It is complex and fragile, and requires that too many things be coordinated out of sight of the user. Matt -- What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead. -- Norbert Wiener -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20110808/b778b0ad/attachment.htm>
