On Tue, Dec 21, 2010 at 21:16, Vijay S. Mahadevan <vijay.m at gmail.com> wrote:
> Jed, I ask because after the restart, the residual changes 10 orders > of magnitude and a-priori, it is quite hard to decide the restart > number. Yes in the test case I presented, the residual gets close > enough to the tolerance and I can afford few more vector storage but > for a much refined problem, this might not be the case and so it > worries me. > What happens if you run with -ksp_gmres_modifiedgramschmidt? This is slow in parallel, but provides insight into what is causing the problem. My initial tests with bcgs were not satisfactory (very bad convergence > as compared to gmres) but I tried GCR just now and it seems to > converge correctly to the right solution, monotonically for the same > problem. > GCR provides a cheap way to access the solution, see what it does with monitor_true_residual. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20101221/17357d8e/attachment-0001.htm>
