Hi Jed, Thanks a lot, it works after switching to the right . But can you say a little more about what happened in the first scenario, I did not quite fellow you. Let's say, If I set -ksp_rtol 1e-2, what does this mean in the left PC case. More specifically, which term will be considered as a stop creteria for the KSP solve.
Yan On Tue, Sep 15, 2009 at 6:27 PM, Jed Brown <jed at 59a2.org> wrote: > Ryan Yan wrote: > > How can I explain the relative tolerance is function correctly? as you > can > > see from the term ||Ae||/||Ax||, neither of my testruns seems to stop at > the > > right place(should be 10^(-2), 10^(-3) respectively). > > The ||Ae||/||Ax|| column is not the preconditioned norm. You are using > left-preconditioned GMRES (the default) which uses the preconditioned > norm. Use > > -ksp_right_pc -ksp_norm_type unpreconditioned > > for the behavior you seem to expect. > > Jed > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20090915/5f7c2391/attachment.htm>
