a question about tolerance

Ryan Yan vyan2000 at gmail.com
Tue Sep 15 18:04:23 CDT 2009

Thanks Jed.

And in the term ||Ae||/||Ax||,  PETSc impilictly assume that we use zero as
initial guess and here the x really means exact solution, right?


On Tue, Sep 15, 2009 at 6:41 PM, Jed Brown <jed at 59a2.org> wrote:

> Ryan Yan wrote:
> > 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.
> Look at the first column (preconditioned residual norm).  Notice that
> this is decreasing by 1e-2 and 1e-3 respectively in your examples.
> Jed
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20090915/d0631ca9/attachment.htm>

More information about the petsc-users mailing list