[Users] [Commits] [svn:einsteintoolkit] WeylScal4/trunk/test/teukolsky/ (Rev. 129)

[Ian Hinder]

On 27 Nov 2012, at 14:10, Erik Schnetter <schnetter at cct.lsu.edu> wrote:

> The reason for this change was the past timelevels were left uninitialised after postregridinitial. The previous sequence was:
> 1. fill timelevels
> 2. regrid
> 3. postregridinitial on current timelevel
> 
> This leaves the past timelevels potentially uninitialised. And when init_fill_timlevels is set, then no other method will set up these past timelevels. Things work fine if this regridding step is a no-op, which will be the case for most current setups, as in this case the past timelevels remain defined.
> 
> My change re-applied the "fill timelevels" after postregridinitial. This should be a no-op, except if postregridinitial modified the current timelevel. In this case, copying these data to the past timelevels is arguably the correct thing to do.

Thanks for the info.  So in most common cases, the effect of this change is to effectively apply postregridinitial to the past timelevels (via copying from the current timelevel which has had this applied) where it was previously not being applied.  This could conceivably mean that some things which were computed exactly from the initial data on the past timelevels are now no longer exact, having been "recomputed" by postregridinitial, but this is no worse than what is done on the current timelevel, so while it is different, it is not wrong.

> 
> -erik
> 
> 
> 
> On Tue, Nov 27, 2012 at 3:03 AM, Ian Hinder <ian.hinder at aei.mpg.de> wrote:
> 
> On 27 Nov 2012, at 08:39, rhaas at tapir.caltech.edu wrote:
> 
> > User: rhaas
> > Date: 2012/11/27 01:39 AM
> >
> > Modified:
> > /trunk/test/teukolsky/
> >  Psi4i.d.asc, Psi4i.x.asc, Psi4i.y.asc, Psi4i.z.asc, Psi4r.d.asc, Psi4r.x.asc, Psi4r.y.asc, Psi4r.z.asc
> >
> > Log:
> > WeylScal4: regenerate test data after Carpet change
> >
> > Carpet's 6b5c318bb1057851d0ee1b5bba6e633c5cf31ca6 which re-copies
> > init_fill_timelevels after initial restriction affects the ID we see and hence
> > the final answer
> 
> Hi all,
> 
> This sounds like it might change results for more than just this one test case.  Does more test data need to be regenerated, and does this affect reproducibility of simulations?  Erik, what was the reason for this change in Carpet?  Am I worrying for nothing?
> 
> --
> Ian Hinder
> http://numrel.aei.mpg.de/people/hinder
> 
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> 
> 
> -- 
> Erik Schnetter <schnetter at cct.lsu.edu>
> http://www.perimeterinstitute.ca/personal/eschnetter/

-- 
Ian Hinder
http://numrel.aei.mpg.de/people/hinder

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