On Tue, Dec 21, 2010 at 21:04, Barry Smith <bsmith at mcs.anl.gov> wrote:
> This is a sign that the preconditioner is seriously messed up and should > not be used in its current form. It can happen if the matrix is nearly > singular and for example you use an incomplete factorization for a > preconditioner that just screws up the scaling like totally. Run with > -ksp_monitor_true_residual and you'll see that the solver is not really > solving the problem even though it thinks it is converging fine. FGMRES only does right preconditioning so it should be showing the true residual. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20101221/330a8c09/attachment.htm>
