There is a bit of complicated logic to determine the "adjusted" timestep in
TSAdaptChoose() when if (*accept && ts->exact_final_time ==
TS_EXACTFINALTIME_MATCHSTEP) {
Is it possible that hmax = tmax - t; is exactly zero, and the logic below
does not correctly handle that case?
0 TS dt 0. time 0.
0 TS dt 0. time 0.
0 TS dt 0. time 0.
0 TS dt 0. time 0.
TSAdapt basic step 0 stage rejected (SNES reason DIVERGED_FNORM_NAN)
t=0 + 0.000e+00 retrying with dt=0.000e+00
TSAdapt basic step 0 stage rejected (SNES reason DIVERGED_FNORM_NAN)
t=0 + 0.000e+00 retrying with dt=0.000e+00
TSAdapt basic step 0 stage rejected (SNES reason DIVERGED_FNORM_NAN)
t=0 + 0.000e+00 retrying with dt=0.000e+00
TSAdapt basic step 0 stage rejected (SNES reason DIVERGED_FNORM_NAN)
t=0 + 0.000e+00 retrying with dt=0.000e+00
TSAdapt basic step 0 stage rejected (SNES reason DIVERGED_FNORM_NAN)
t=0 + 0.000e+00 retrying with dt=0.000e+00
TSAdapt basic step 0 stage rejected (SNES reason DIVERGED_FNORM_NAN)
t=0 + 0.000e+00 retrying with dt=0.000e+00
TSAdapt basic step 0 stage rejected (SNES reason DIVERGED_FNORM_NAN)
t=0 + 0.000e+00 retrying with dt=0.000e+00
TSAdapt basic step 0 stage rejected (SNES reason DIVERGED_FNORM_NAN)
t=0 + 0.000e+00 retrying with dt=0.000e+00
TSAdapt basic step 0 stage rejected (SNES reason DIVERGED_FNORM_NAN)
t=0 + 0.000e+00 retrying with dt=0.000e+00
TSAdapt basic step 0 stage rejected (SNES reason DIVERGED_FNORM_NAN)
t=0 + 0.000e+00 retrying with dt=0.000e+00
TSAdapt basic step 0 stage rejected (SNES reason DIVERGED_FNORM_NAN)
t=0 + 0.000e+00 retrying with dt=0.000e+00
Sophie,
Any idea why SNES reason DIVERGED_FNORM_NAN? Could you run with
-snes_error_if_not_converged?
> On Dec 13, 2024, at 2:34 PM, Blondel, Sophie <[email protected]> wrote:
>
> Hi everyone,
>
> The first max time it is trying to reach is 1.0e-12 s, and the initial dt is
> set to 1.0e-12 s from the commandline options. I believe it's not a
> formatting issue and that the dt is actually set somewhere to 0 s because
> that's why the step is rejected.
>
> Best,
>
> Sophie
> From: Barry Smith <[email protected] <mailto:[email protected]>>
> Sent: Friday, December 13, 2024 14:21
> To: Blondel, Sophie <[email protected] <mailto:[email protected]>>; Jed Brown
> <[email protected] <mailto:[email protected]>>; Zhang, Hong
> <[email protected] <mailto:[email protected]>>; Emil Constantinescu
> <[email protected] <mailto:[email protected]>>
> Cc: [email protected] <mailto:[email protected]>
> <[email protected] <mailto:[email protected]>>;
> [email protected]
> <mailto:[email protected]>
> <[email protected]
> <mailto:[email protected]>>
> Subject: Re: [petsc-users] "-ts_exact_final_time matchstep" leads to
> DIVERGED_STEP_REJECTED
>
>
> Hm, what is the final time you are stepping towards in this run?
>
> There is something wrong with the adapt code since it seems to start with
> a dt of 0 but then tries "adapting" several times, but it could be the
> monitor function does not correctly format numbers smaller than 1.e-12 and it
> is just using truly small dt.
>
> Jed, Hong, Emil?
>
> Barry
>
>
>> On Dec 10, 2024, at 11:08 AM, Blondel, Sophie <[email protected]
>> <mailto:[email protected]>> wrote:
>>
>> Good morning Barry,
>>
>> Attached are the updated files, there is more useful information in them.
>>
>> Cheers,
>>
>> Sophie
>>
>> From: Blondel, Sophie via Xolotl-psi-development
>> <[email protected]
>> <mailto:[email protected]>>
>> Sent: Monday, December 9, 2024 17:29
>> To: Barry Smith <[email protected] <mailto:[email protected]>>
>> Cc: [email protected] <mailto:[email protected]>
>> <[email protected] <mailto:[email protected]>>;
>> [email protected]
>> <mailto:[email protected]>
>> <[email protected]
>> <mailto:[email protected]>>
>> Subject: Re: [Xolotl-psi-development] [petsc-users] "-ts_exact_final_time
>> matchstep" leads to DIVERGED_STEP_REJECTED
>>
>> Hi Barry,
>>
>> I hope you are doing well.
>>
>> Attached are the output. To give a little more context, this is a "new" way
>> of running the code where multiple instances are created and communicate
>> together every few time steps (like coupling the code with itself in
>> memory). Here there are 3 instances that each have a separate TS object,
>> plus one "main" instance that doesn't solve anything but compute rates to
>> exchange between the other instances.
>>
>> Cheers,
>>
>> Sophie
>>
>> From: Barry Smith <[email protected] <mailto:[email protected]>>
>> Sent: Monday, December 9, 2024 15:12
>> To: Blondel, Sophie <[email protected] <mailto:[email protected]>>
>> Cc: [email protected] <mailto:[email protected]>
>> <[email protected] <mailto:[email protected]>>;
>> [email protected]
>> <mailto:[email protected]>
>> <[email protected]
>> <mailto:[email protected]>>
>> Subject: Re: [petsc-users] "-ts_exact_final_time matchstep" leads to
>> DIVERGED_STEP_REJECTED
>>
>>
>>
>>> On Dec 9, 2024, at 2:56 PM, Blondel, Sophie via petsc-users
>>> <[email protected] <mailto:[email protected]>> wrote:
>>>
>>> Hi,
>>>
>>> I am trying to understand a strange behavior I'm encountering: when running
>>> my application with "-ts_exact_final_time stepover" everything goes well,
>>> but when I switch to "matchstep" I get DIVERGED_STEP_REJECTED before the
>>> first time step is finished.
>>
>> This is in the very first time-step in TSSolve?
>>
>> Please run with -ts_monitor and send all the output (best for a short
>> time interval and do it twice once with -ts_exact_final_time stepover and
>> once with exact.
>>
>> Barry
>>
>>
>>> I tried increasing the maximum number of rejections and it just takes
>>> longer to diverge, and if I set the value to "unlimited" it is basically an
>>> infinite loop.
>>>
>>> Is there a way to check why is the step rejected? Could the "matchstep"
>>> option change tolerances somewhere that would cause that behavior?
>>>
>>> Let me know if I should provide more information.
>>>
>>> Best,
>>>
>>> Sophie Blondel
