On Wed, Mar 20, 2013 at 2:00 PM, Mark F. Adams <mark.adams at columbia.edu>wrote:
> > On Mar 20, 2013, at 2:12 PM, Mehrdad H Farahani <mh.farahani at gmail.com> > wrote: > > > I'm experience a weird convergence problem with bcgsl with both ILU and > GAMG preconditioning. The problem converges normally (at least in the > preconditioned norm), but then kicks out with converged reason = -4. I've > attached the convergence history of the previous time-step which worked and > the timestep which shows problems. Could someone give me an idea on how to > proceed? > > > > Did you run with -ksp_converged_reason ? > > I don't know were this -4 comes from. Could this be from your code? > Some people call KSPGetConvergedReason(), but then don't compare to the enums and don't convert to a string using KSPConvergedReasons[reason]. http://www.mcs.anl.gov/petsc/petsc-dev/docs/manualpages/KSP/KSP_DIVERGED_DTOL.html The problem is likely that your preconditioner is singular. What sort of problem are you solving? -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20130320/4b14b34f/attachment.html>
