[petsc-users] KSP no longer returning NaNs?

[Matthew Knepley]

On Wed, Jul 25, 2012 at 5:04 PM, Jed Brown <jedbrown at mcs.anl.gov> wrote:

> On Wed, Jul 25, 2012 at 4:58 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:
>
>>
>>   As always a COMPLETE error report is useful. There are a million ways
>> you could see this change in behavior but we can't spend time guessing.  At
>> a minimum please send the entire error output.
>>
>>    I note in 3.3 the KSPDefaultConverged() still checks for NAN and
>> returns a negative converged reason (not an error) so I can only guess why
>> you are getting different behavior without more information.,
>>
>
> This is probably the main complaint:
>
> http://petsc.cs.iit.edu/petsc/petsc-dev/rev/7d6f5cbe67bc
>

Yes, but what in PETSc code could possibly create these NaNs?

   Matt


>
>
>>
>>
>>      Barry
>>
>> On Jul 25, 2012, at 4:35 PM, Kirk, Benjamin (JSC-EG311) wrote:
>>
>> > Hello -
>> >
>> > I've been using PETSc 3.1 for quite a while now and have been hesitant
>> to
>> > upgrade because of some new behavior I found in 3.2.  Let me explain...
>> >
>> > In petsc-3.1, if the KSP encountered a NaN it would return it to the
>> > application code.  We actually liked this feature because it gives us an
>> > opportunity to catch the NaN and attempt recovery, in our case by
>> decreasing
>> > the time step and trying again.
>> >
>> > It seems in petsc-3.2, however, that PETSc itself aborts internally, so
>> we
>> > are unable to recover from the situation.
>> >
>> > Is there any way to get the old behavior back?
>> >
>> > Thanks,
>> >
>> > -Ben
>> >
>>
>>
>


-- 
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
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