[Users] Stop MoL after tolerance is reached

[Erik Rodrígo Jiménez Vázquez]

Thank you!, the method that you give me to stop the evolution, works
perfectly. However, there is an error, I can't read the output data as
initial data for my Brill wave evolution.

My thorn IDBrillMoL evolves the conformal factor (which I named phi because
the initial data is obtained through a wave-like equation), and when the
criteria is reached, it stops the evolution and saves a checkpoint with
that iteration. For the evolution I wrote a thorn named BrillEvolve and I
assigned memory to a variable named "brillpsi" which will store the initial
conformal factor. When I read the data (checkpoint) I got the error:  No
matching variable found for 'IDBRILLMOL::phi'

According to the readingfile interface, I can read a variable and set in a
different variable with the option alias, so, I try

IO::filereader_ID_vars  = "BrillEvolve::brillpsi{alias='IDBRILLMOL::phi'}"

but I got the error above described. Can you help me with this? Am I
misunderstanding how the readingfile interface works?

Erik


El lun., 14 oct. 2019 a las 9:44, Haas, Roland (<rhaas at illinois.edu>)
escribió:

> Hello Erik,
>
> as to how to decide to stop: the simplest way would be to compute a
> pointwise stopping criterion (maybe magnitude of the right-hand-side or
> so) then do a reduction on it using the CCTK_Reduce function
> (assuming you are using Carpet), see eg. the code in Hydro_Analysis to
> compute the center of mass:
>
>
> https://bitbucket.org/einsteintoolkit/einsteinanalysis/src/master/Hydro_Analysis/src/CoreCentroid.c#lines-100
>
> the function itself is documented here:
>
> https://www.einsteintoolkit.org/usersguide/UsersGuidech9.html#verbatim-63
>
> Once you have decided to stop, terminate the simulation by calling
> CCTK_TerminateNext
> (
> https://www.einsteintoolkit.org/referencemanual/ReferenceManualch2.html#x4-192000A2
> )
> making sure to have enabled the option to write a checkpoint when
> terminating (io::checkpoint_on_terminate = yes).
>
> You can read data from the checkpoint as initial data using the
> filereader interface
>
>
> https://www.einsteintoolkit.org/thornguide/CactusBase/IOUtil/documentation.html#x1-1000010
>
> and if you need to change grid structure, you can use the
> ReadInterpolate thorn
> (https://github.com/rhaas80/ReadInterpolate/tree/master/ReadInterpolate),
> which is however a bit more complex to use.
>
> If you need to change data in between what was checkpointed and what
> needs to be evolved you will have to add routines to the INITIAL bin
> after IOUtil_RecoverIDFromDatafiles (see IOUtil's schedule.ccl).
>
> Hope this helps getting you started.
>
> Yours,
> Roland
>
> > Dear all
> >
> > I'm trying to construct Brill wave initial data by transforming the
> > elliptic pde equation for the conformal factor in to a wave-like equation
> > with a source. After reaching a stationary state, I want to stop the
> > evolution and give the stationary state as an initial data for the BSSN
> > system.
> >
> > I'm evolving the wave-like equation with MoL and my question is, How can
> I
> > stop the MoL evolution if the solution reaches the numerical tolerance
> and
> > then pass it as initial data?
> >
> > Erik
>
>
>
> --
> My email is as private as my paper mail. I therefore support encrypting
> and signing email messages. Get my PGP key from http://pgp.mit.edu .
>
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