[petsc-users] Turning off TSADAPT still adapts time step

[Mark Lohry]

To continue beating this horse, I wrote this:

PetscErrorCode CheckStageTrue(TSAdapt adapt,TS ts,PetscBool *accept){
   *accept = PETSC_TRUE;
}

   TSAdaptSetCheckStage(adapt,CheckStageTrue);


But TSAdapt then still rejects the stage, but quits altogether instead 
of continuing:

   Nonlinear solve did not converge due to DIVERGED_LINEAR_SOLVE 
iterations 4
       TSAdapt 'basic': step   0 stage rejected t=0          + 1.000e-01 
retrying with dt=2.500e-02


Am I not using TSAdaptSetCheckStage correctly?




On 04/27/2015 12:55 PM, Jed Brown wrote:
> Mark Lohry <mlohry at princeton.edu> writes:
>
>> TSAdaptChoose_None is being called, yes. Output with -ts_adapt monitor
>> looks like this:
>>
>>         TSAdapt 'none': step  17 accepted t=680        + 4.000e+01
>> family='beuler' scheme=0:'(null)' dt=4.000e+01
>>         TSAdapt 'none': step  18 accepted t=720        + 4.000e+01
>> family='beuler' scheme=0:'(null)' dt=4.000e+01
>>         TSAdapt 'none': step  19 accepted t=760        + 4.000e+01
>> family='beuler' scheme=0:'(null)' dt=4.000e+01
>>         TSAdapt 'none': step  20 stage rejected t=800        + 4.000e+01
>> retrying with dt=1.000e+01
> Add -snes_converged_reason.  What do you want to do when the solver
> fails?  Pretend like it succeeded and get the wrong answer?  Usually
> people shorten the time step and retry, which is what you see happening
> here.
>
> You can call TSAdaptSetCheckStage and have your function unconditionally
> set accept to PETSC_TRUE (and you'll likely get the wrong answer).