Thank you Barry for your suggestions. The error I get is now KSP_DIVERGED_INDEFINITE_PC. The matrix that I try to invert is actually symmetric and positive definite. I was not aware that this can lead to a indefinite preconditioner. If I use a Jacobi preconditioner or tell BoomerAMG that the matrix is symmetric I don't encounter any errors. So I'm quite for now :-)
Daniel > Daniel, > > That message is not coming from PETSc so likely Deal.II is processing > the result from KSPConvergedReason() and generating that less then totally > useful output. If you run with -ksp_converged_reason PETSC will (if Deal.II > processes PETSc options correctly) print a more complete reason. > > Off hand I am guessing that CG detected a non-symmetric or indefinite > matrix or preconditioner which it cannot handle so it barfed out. You can run > with GMRES instead of CG and if that converges then this is the likely > explanation. > > Barry > > > On Dec 11, 2012, at 8:19 AM, Daniel Arndt <daniel.arndt at > stud.uni-goettingen.de > <https://lists.mcs.anl.gov/mailman/listinfo/petsc-users>> wrote: > > >/ Hello everyone, > />/ > />/ at the moment I'm trying to solve a Poisson problem with SIPG > />/ stabilization and discontinuous finite elements. The matrix is > />/ constructed in deal.II. When I try to solve this problem with PETSc's CG > />/ solver and a BlockJacobi preconditioner or a BoomerAMG preconditioner > />/ from the Hypre package I get this weird error message. > />/ > />/ Exception on processing: > />/ Iterative method reported convergence failure in step 3 with residual > />/ 1.50616 > />/ Aborting! > />/ > />/ Since the solver is allowed to take 5000 steps this convergence failure > />/ is clearly early. Did anyone encounter such an error before? What can > />/ produce such an early convergence failure? > />/ > />/ Thanks in advance, > />/ Daniel > />/ > />/ > />/ > / -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20121211/acf178bc/attachment.html>
