On Tue, Jul 10, 2012 at 1:34 PM, Paul T. Bauman <ptbauman at gmail.com> wrote:
> Greetings, > > This question is somewhat related to this thread: > http://lists.mcs.anl.gov/pipermail/petsc-users/2011-August/009583.html but > instead of resurrecting that thread, I decided to start a new one. > > Summary: In the libMesh wrapper of PETSc's KSP, a call is made to > KSPSetOperators; I gather this is in order to allow reusing the same > preconditioner, if desired. However, I've noticed that when I use the > following options, the sub-preconditioner type gets reset: > > -pc_type bjacobi -sub_pc_type ilu -sub_pc_factor_mat_solver_package superlu > > In particular, the first linear solve uses what I asked for, but in all > following linear solves, the petsc ilu solver is used instead of superlu. > If I remove the KSPSetOperators call, everything is peachy. > > My question: Does a call need to be made to PCSetFromOptions (or something > similar...) to keep the superlu ilu solver around or would that wipe out > the KSPSetOperators effect? Is this a PETSc bug? Other? > > This is with petsc-3.3-p1. > Sorry to reply to myself, but I read this and realized I was rather imprecise. The KSPSetOperators call I referred to is in the solve step. In particular, KSPSetFromOptions is called during initilization, only once, but KSPSetOperators is called each time solve is called. I was able to mimic my problem in the attached, slightly modified ksp/ex5.c, running with: mpiexec -np 6 ./ex5 -ksp_type gmres -pc_type bjacobi -sub_pc_type ilu -ksp_view -ksp_monitor -sub_pc_factor_mat_solver_package superlu -sub_pc_factor_levels 1 Is the correct solution just to call KSPSetFromOptions every time? Will that be noticeable at all? I hope this was less vague than my original message. Thanks again. Best, Paul -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20120710/89dcc497/attachment.html> -------------- next part -------------- A non-text attachment was scrubbed... Name: ex5.c Type: text/x-csrc Size: 12302 bytes Desc: not available URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20120710/89dcc497/attachment.c>
