[petsc-users] Convergence problem in newton iteration

[Matthew Knepley]

On Tue, Jan 7, 2014 at 4:09 PM, Danyang Su <danyang.su at gmail.com> wrote:

> Hi All,
>
> I have implemented the KSP solver to a CFD problem and it works well for
> most of the scenarios. But for some scenarios, it will give out solution 0.
>
> The matrix structure, rhs and solution from PETSc and another sequential
> solver can be found in the attached files. Please note that the first value
> is the number of data in the file.
>
> For linear equations 1 to 48, it works well and the solutions are the same
> as the other solver. For equation 49, PETSc give out zero solution and the
> iteration number is 0, but the other solver give out acceptable solution.
> The KSPConvergencedReason is 3 for all these equations.
>

This means that the solver converged because it went below the absolute
tolerance. You could have a poorly scaled system.

   Matt


> All suggestions and comments are appreciated.
>
> Regards,
>
> Danyang
>
>
>
>


-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20140107/16ab1809/attachment.html>