I am doing a transient computation, solving one linear problem per timestep, so naturally I want to exploit 'x' from the previous time step to be the initial value for the next solve (KSPSetInitialGuessNonzero). For the longest time, however, I was getting wrong results, unless I was resetting 'x' each time step (to some constant value, pure zero caused bcgs to break down). After hours of debugging I was unable to find any errors in my coefficients, I experimentally found out, however, that changing the solver from bcgs to gmres or fgmres removes the problem: I no longer need to clear the solution vector. Now I am a bit worried, if this is still some time bomb in my code or is a known phenomenon. Thanks for any hints.
Regards, Dominik -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20111021/464fd6c9/attachment.htm>
