[Users] Grid function timelevels

[Erik Schnetter]

Jens

My previous instructions were unclear: You need to set up zeroth order
TIME interpolation. SPACE interpolation can be any order. If your
function is constant in time, this will not reduce accuracy.

-erik


On Tue, Jul 3, 2018 at 10:22 AM, Erik Schnetter <schnetter at cct.lsu.edu> wrote:
> Jens
>
> What you are doing is correct, and I would not worry about the inefficiencies.
>
> Another, more complicated way, would be the following:
> - Since your variable is constant, you declare it and you allocate
> only a single time level
> - You then don't have to copy any time levels; the current value will
> be preserved
> - Whenever your interpolate in time, which might happen implicitly
> during spatial interpolation or during prolongation, you need to
> ensure that you use zeroth (0th) order interpolation, i.e. are taking
> values from the nearest available value. Telling all the respective
> part of Cactus and Carpet to do so might be inconvenient, and is
> overall probably not worth the trouble.
>
> -erik
>
>
>
> On Tue, Jul 3, 2018 at 9:57 AM, Jens Mahlmann <jensmahl at alumni.uv.es> wrote:
>> Dear all,
>>
>> I am currently optimizing some code in the Einstein Toolkit and have a
>> general question on time levels and declarations.
>>
>> Throughout my evolution, I use some quantities (initialized as grid
>> functions with various time levels) which are not changed throughout the
>> evolution or only changed explicitly in some moments. At the moment, I
>> make sure in every time step via
>>
>> variable[i3D] = variable_p[i3D]
>>
>> that I have the correct values at the respective time.
>>
>> Is there a better way to do this? I.e. is there a way to declare a grid
>> function or to register it such that it stays untouched throughout the
>> time evolution except when I change it explicitly?
>>
>> Thank you very much and my best from Valencia
>>
>> Jens Mahlmann
>>
>> _______________________________________________
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>
>
>
> --
> Erik Schnetter <schnetter at cct.lsu.edu>
> http://www.perimeterinstitute.ca/personal/eschnetter/



-- 
Erik Schnetter <schnetter at cct.lsu.edu>
http://www.perimeterinstitute.ca/personal/eschnetter/