[petsc-users] [TimeStepping] Eventhandler

[Moritz Huck]

Hi,

I see I am sorry, I misinterpreted the output -ts_adapt_monitor.

You are right point 2 is not an issue.

I there a way to let the time stepping continue with the last time step 
instead of the initial time step?

Best Regards,

Moritz

Am 03.02.19 um 17:04 schrieb Zhang, Hong:
> ex40 seems to work fine. Here is the output with -ts_monitor -ts_event_monitor -ts_dt 0.01 :
>
> 8 TS dt 0.5 time 3.11
> 9 TS dt 0.5 time 3.61
> TSEvent: iter 0 - Event 0 interval detected [3.61 - 4.11]
> 9 TS dt 0.467955 time 3.61 (r)
> TSEvent: iter 1 - Stepping forward as no event detected in interval [3.61 - 4.07796]
> 10 TS dt 0.00365179 time 4.07796
> TSEvent: iter 2 - Stepping forward as no event detected in interval [4.07796 - 4.08161]
> 11 TS dt 2.5403e-05 time 4.08161
> TSEvent: Event 0 zero crossing at time 4.08163 located in 3 iterations
> Ball hit the ground at t =  4.08 seconds
> 12 TS dt 0.0283673 time 4.08163
> 13 TS dt 0.01 time 4.11
> 14 TS dt 0.1 time 4.12
>
> The event occurs during the step [3.61- 4.11]. After the event is located at 4.08163, the next step after the event should be 4.11-4.08163 = 0.02837 (see 12 TS) to complete the original step. After 4.11, the specified initial stepsize dt=0.01 will be used.
>
> Hong (Mr.)
>
>> On Feb 3, 2019, at 6:08 AM, Moritz Huck via petsc-users <petsc-users at mcs.anl.gov> wrote:
>>
>> Hi Barry,
>>
>> src/ts/examples/tutorials/ex40.c (run with ARKIMEX3 and initial dt=1e-2) has the same behavior:
>>
>> TSEvent: iter 0 - Event 0 interval detected [3.61 - 4.11]
>> TSEvent: iter 1 - Stepping forward as no event detected in interval [3.61 - 4.07796]
>> TSEvent: iter 2 - Stepping forward as no event detected in interval [4.07796 - 4.08161]
>> TSEvent: Event 0 zero crossing at time 4.08163 located in 3 iterations
>> Ball hit the ground at t =  4.08 seconds
>>        TSAdapt basic arkimex 0:3 step  13 accepted t=4.11       + 1.000e-02 dt=1.000e-01  wlte=    0  wltea=   -1 wlter=   -1
>>
>>        TSAdapt basic arkimex 0:3 step  14 accepted t=4.12       + 1.000e-01 dt=5.000e-01  wlte=    0  wltea=   -1 wlter=   -1
>>
>> It continues at the end of the "event interval" with the initial timestep.
>>
>> Best Regards,
>>
>> Moritz
>>
>>
>>
>>
>> Am 03.02.19 um 02:43 schrieb Smith, Barry F.:
>>>> On Feb 2, 2019, at 12:08 PM, Moritz Huck via petsc-users <petsc-users at mcs.anl.gov> wrote:
>>>>
>>>> Hi,
>>>> I am trying to use SetEventHandler.
>>>> I hav eencountered two "problems":
>>>>
>>>> 1. after an event is encountered the next time step is needlessly small (h=1e-6), even if a don't change anything in the function (for testing).
>>>>
>>>>
>>>> 2. the integration does not continue at the event encounter
>>>> e.g. my eventfunction is g(t,u)=t-1,
>>>> the event is found in the step from t= 0.9 to 1.1 at tevent=1
>>>> but the next step is not 1+dt but it is 1.1 + dt
>>>> I would expect the next step to be 1.+dt
>>>       Hmm, this sounds like it could be an error. Could you send us a simple code that exhibits it?
>>>
>>>     Thanks
>>>
>>>     Barry
>>>
>>>> Best Regards,
>>>> Moritz
>>>>