[Users] Multiple time levels

[Steven R. Brandt]

On 01/05/2016 03:39 PM, Erik Schnetter wrote:
> You can set the prologation type of "mask" such that it is never
> prolongated, then you don't need a second time level.
Yes, except, unfortunately, that I need to have it prolonged.
>
> I'll need more details to investigate. Do you receive warnings at
> startup about prolongation?
None.

Cheers,
Steve
>
> -erik
>
> On Tue, Jan 5, 2016 at 4:34 PM, Steven R. Brandt <sbrandt at cct.lsu.edu> wrote:
>> On 01/05/2016 03:23 PM, Erik Schnetter wrote:
>>> If you have n time levels, then it is natural to set
>>> prolongation_order_time = n-1.
>> Originally, the error message occurred for a variable named mask, which had
>> a single time level. I guessed that since the error message showed a single,
>> wrong value, that having two time levels to choose from might make it work.
>> So I gave mask two time levels and started copying in CCTK_PRESTEP. The
>> error then showed up in eta, which always had 2 timelevels (because it's
>> evolved with RK3).
>>>
>>> When does the error occur? Does it happen during initial data setup,
>>> or during evolution? Applying boundary conditions for the initial
>> Iteration 0 prints, so evolution.
>>> conditions also requires prolongation. Depending on your initial data
>>> scheme, you may even be applying boundary conditions to past time
>>> levels for the initial conditions.
>> Not sure I follow what you're saying here. I calculate all data for time =
>> 0.
>>
>> Cheers,
>> Steve
>>
>>> -erik
>>>
>>>
>>> On Tue, Jan 5, 2016 at 4:11 PM, Steven R. Brandt <sbrandt at cct.lsu.edu>
>>> wrote:
>>>> OK, so copying data in CCTK_PRESTEP seems to work.
>>>>
>>>> My next question is, I think, trickier... My par file looks something
>>>> like
>>>> this
>>>>
>>>> Carpet::time_refinement_factors = "[1,1]"
>>>> Time::timestep_method = "given"
>>>> Time::timestep = 0.05
>>>> Carpet::prolongation_order_time = 0
>>>> ...
>>>>
>>>> Unfortunately, when I try to run the code I get this:
>>>>
>>>> WARNING level 0 from host 18-5e-f-12-9b-2a.wlan.lsu.edu process 0
>>>>     while executing schedule bin (none), routine (no thorn)::(no routine)
>>>>     in thorn CarpetLib, file
>>>>
>>>> /home/sbrandt/cactus/CactusFW/arrangements/Carpet/CarpetLib/src/gdata.cc:375:
>>>>     -> Internal error: extrapolation in time. variable=FUNWAVE::eta
>>>> time=0
>>>> times=[0.050000000000000003]
>>>> cactus_sim:
>>>>
>>>> /home/sbrandt/cactus/CactusFW/arrangements/Carpet/Carpet/src/helpers.cc:269:
>>>> int Carpet::Abort(const cGH*, int): Assertion `0' failed.
>>>>
>>>> It's trying to get data from the same time level, but it seems to only
>>>> have
>>>> the wrong one.
>>>>
>>>> My theory is that prolongation_order_time = 1 is going to give me what I
>>>> want, because it's going to prolong to one of the endpoints (the code
>>>> runs,
>>>> at least). Does this mean that prolongation_order_time = 0 is broken?
>>>>
>>>> Cheers,
>>>> Steve
>>>>
>>>>
>>>> On 01/05/2016 01:06 PM, Erik Schnetter wrote:
>>>>> Steve
>>>>>
>>>>> If a grid variable has multiple time levels, then it will be cycled at
>>>>> the beginning of every time step. You need to copy the past to the
>>>>> current time level after time level cycling to preserve the previous
>>>>> behaviour.
>>>>>
>>>>> -erik
>>>>>
>>>>>
>>>>> On Tue, Jan 5, 2016 at 1:46 PM, Steven R. Brandt <sbrandt at cct.lsu.edu>
>>>>> wrote:
>>>>>> In the code I'm working on, I have a set of variables living at a
>>>>>> single
>>>>>> timestep. For various reasons, I want to shift to having them at two
>>>>>> timelevels, but simply making the change in interface and schedule
>>>>>> results in failure to run old test suites. Is there a recipe I should
>>>>>> be
>>>>>> following to make this work?
>>>>>>
>>>>>> Cheers,
>>>>>> Steve
>>>>>> _______________________________________________
>>>>>> Users mailing list
>>>>>> Users at einsteintoolkit.org
>>>>>> http://lists.einsteintoolkit.org/mailman/listinfo/users
>>>>>
>>>>>
>>>
>
>