[petsc-users] TimeStepper norm problems. EMIL Please read this

[Andrew Spott]

awesome, great to hear.




Thanks!




-Andrew

On Tue, Mar 31, 2015 at 7:16 PM, Emil Constantinescu <emconsta at mcs.anl.gov>
wrote:

> Hi Andrew - we found a bug in TSComputeRHSFunctionLinear.
> In your code you need to provide the context to TSSetRHSFunction:
> TSSetRHSFunction( tss, NULL, TSComputeRHSFunctionLinear, &c );
> For now you can check out a branch that has implemented the fix by 
> running git checkout emil/fix-ts-dae-rebased-v2 and then make everything.
> The fix is at 
> https://bitbucket.org/petsc/petsc/commits/557d2b190687a728e86290bdc604ce0d2dc53473
> This is working for us.
> We'll push the fix soon in master.
> Emil
> -- 
> Emil M. Constantinescu, Ph.D.
> Computational Mathematician
> Argonne National Laboratory
> Mathematics and Computer Science Division
> 9700 S Cass Avenue,
> Argonne, IL 60439, USA
> Ph: 630-252-0926
> http://www.mcs.anl.gov/~emconsta
> On 3/30/15 9:32 PM, Andrew Spott wrote:
>> I’m sorry, I didn’t want to imply you were taking too much time.  I was
>> just interested in trying to solve the problem myself, especially if it
>> was a simpler fix.
>>
>> I don’t have enough of an understanding of the internals of PETSc
>> though, if it depends on the compiler flags.
>>
>> Good luck!
>>
>> -Andrew
>>
>> —
>> Andrew
>>
>>
>> On Mon, Mar 30, 2015 at 7:23 PM, Emil Constantinescu
>> <emconsta at mcs.anl.gov <mailto:emconsta at mcs.anl.gov>> wrote:
>>
>>     Hi Andrew,
>>
>>     Sorry for the delay; things are going slower with me over the spring
>>     break but we are working on it.
>>
>>     The problem that you see may not be related to the integrator, which
>>     runs well (we get expected convergence rates and good results) for
>>     other
>>     problems, in particular, for problems with real variables (and no
>>     c++11). So the high level th->endpoint implementation seems fine.
>>
>>     For some reason the linear solver is misbehaving when using cn. If you
>>     use option -snes_mf the problem disappears.
>>
>>     Please do not use -ts_theta_adapt until it is fixed.
>>
>>     In conclusion I don't think that looking at theta.c will be productive.
>>     We are currently looking at what happens at the lower levels.
>>
>>     Thanks,
>>     Emil
>>
>>     On 3/30/15 4:25 PM, Andrew Spott wrote:
>>      > Emil: If I want to fix this myself, do you have any idea where I
>>     should
>>      > start looking? I assume in the th->endpoint section of
>>     TSStep_Theta in
>>      >
>>     http://www.mcs.anl.gov/petsc/petsc-current/src/ts/impls/implicit/theta/theta.c.html?
>>
>>      >
>>      > Thanks,
>>      >
>>      > -Andrew
>>      >
>>      >
>>      >
>>
>>
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