a question about tolerance

[Ryan Yan]

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?

Yan




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
>
>
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