[petsc-users] Suggestions for code with dof >> 1 ?

[Christophe Ortiz]

On Tue, Oct 15, 2013 at 6:20 PM, Jed Brown <jedbrown at mcs.anl.gov> wrote:

> Christophe Ortiz <christophe.ortiz at ciemat.es> writes:
>
> > Yes ! Actually, that was the problem ! Now I set ARKIMEX1BEE after
> > TSSetFromOptions() and it is much faster ! ARKIMEXA2 seems even faster.
>
> I still recommend configuring this stuff from the command line, and I
> would put TSSetFromOptions last so that you can override anything at
> run-time.
>

Ok.


>
> > Thanks Jed !
> >
> > Now I see that the convergence speed of ARKIMEX depends on where I put
> > TSSetFromOptions().
> >
> > If I do:
> > TSCreate();
> > TSSetFromOptions();
> > TSSetProblemType();
> > TSSetType();
> > TSARKIMEXSetType();
> >
> > then ARKIMEXA2 is very fast.
> >
> > Instead, if I put TSSetFromOptions() somewhere else:
> > TSCreate();
> >
> > TSSetProblemType();
> > TSSetType();
> > *TSSetFromOptions();*
> > TSARKIMEXSetType();
>
> I would use this order:
>
>     TSCreate();
>     TSSetProblemType();  // optional
>     TSSetType();
>     TSARKIMEXSetType();
>     TSSetFromOptions();
>
> > ARKIMEXA2 slows down significantly. I guess that TSSetFromOptions
> overrides
> > something...Any idea ?
>
> Compare the output from -ts_view in both cases.
>

I found where is the problem. I had
set TSARKIMEXSetFullyImplicit(ts,PETSC_TRUE);
I found it produces wrong solutions, either with ARKIMEX3, 1BEE or A2.
Solution becomes negative. Without this option, all ARKIMEX types work very
well and very fast.

Christophe
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20131016/816d5676/attachment.html>