[Users] **large** amplitude changes in WFs from Curie "bbh" parfiles when run in ET_2012_05

[Kelly, Bernard J. (GSFC-660.0)[UNIVERSITY OF MARYLAND BALTIMORE COUNTY]]

Hi Ian and others. Coming back to this unresolved issue ...

I've looked at 1D metric files from a fairly advanced point in the
evolution, and can see no differences in the metric components from the
two evolutions. It's difficult to do precise differencing, since the grids
are not commensurate, as pointed out before.

More directly, I've looked at the WeylScal4 waveforms along the coordinate
axes, and they show no sign of the amplitude discrepancy. Attached is the
output from psi4 along the x-axis at around 120M in the evolution (Med
resolution).

So it looks like the change is in the Multipole extraction. Diffing the
two Multipole thorns (and ignoring test-suite file changes), I only see
minor changes in the schedule.ccl:

8c8
< schedule Multipole_Calc at CCTK_ANALYSIS after (calc_np,PsiKadelia)
---
> schedule Multipole_Calc at CCTK_ANALYSIS after
>(calc_np,PsiKadelia,Accelerator_CopyBack)


Again: has anyone run the Curie-era paper's "bbh" parameter files with a
later release of ET and obtained *exactly* the same WF amplitudes? Or a
difference within 1%?

Bernard

On 11/9/12 1:24 PM, "Kelly, Bernard J. (GSFC-660.0)[UNIVERSITY OF MARYLAND
BALTIMORE COUNTY]" <bernard.j.kelly at nasa.gov> wrote:

>Hi Ian. Thanks for the diagnostic suggestions.
>
>
>On 11/7/12 3:59 PM, "Ian
>Hinder" <ian.hinder at aei.mpg.de> wrote:
>
>>
>>On 7 Nov 2012, at 20:29, "Kelly,
>Bernard J. (GSFC-660.0)[UNIVERSITY OF
>>MARYLAND BALTIMORE COUNTY]"
><bernard.j.kelly at nasa.gov> wrote:
>>
>>> Hi. This may be related to something
>Yosef brought up back in July
>>> ["Differences in results ..." from 26
>July], but I'm seeing sizable
>>> differences in WF amplitudes from Multipole
>when running the parameter
>>> files for the ETK paper (Loeffler et al.).
>>>
>>> Specifically, if I take the parameter file
>>> 
>>>
><Cactus>/par/arXiv:1111.3344/bbh/BBHMedHRes.par
>>> 
>>> ... and run it with a
>Curie (ET_2011_05) executable, my r=30M (2,2) mode
>>> has a peak magnitude
>of just above 0.0027. Rerunning the same parameter
>>> file with *no*
>changes, using the current release, Lovelace
>>>(ET_2012_05),
>>> the same
>peak amplitude is just above 0.00257 -- a drop of almost 5%.
>>> 
>>> Can
>anyone tell me what might be going wrong? Is there some kind of
>>>change
>>>
>in default dissipation that could explain such a large discrepancy?
>>
>>I
>don't think so.  McLachlan with its default parameters has always
>>disabled
>dissipation.  We changed the default of apply_dissipation very
>>recently
>(i.e. after Lovelace) from "true" to "false" (and announced this
>>on the
>list), but the dissipation strength has always defaulted to
>zero.
>>
>>Dissipation in that parameter file is provided by the Dissipation
>thorn,
>>and it uses its default value of epsdiss = 0.2.
>>
>>Could this be
>related to the change in grid structure going from the
>>"git" to the
>"mercurial" version of Carpet?  Are the grid structures the
>>same? You can
>output the grid structure to an ASCII file
>using
>>
>>	Carpet::grid_coordinates_filename       = "carpet-grid.asc"
>
>I'm
>attaching some excerpts from the carpet-grid-coordinates files of both
>runs
>("MedRes" version). They're snapshots from iterations 0, 609, and
>2145. For
>the latter two iterations, the grid does seem to be different in
>the
>y-direction (the only direction without a symmetry boundary), but only
>for
>certain refinement levels. The it=0 output is very different for the
>two
>cases; I'm not sure why.
>
>Also, the Curie executable generated this
>diagnostic information *far*
>more frequently (every 32 iterations) than
>Lovelace (every 384).
>Obviously, the times I've chosen were common to
>both.
>
>>
>>Can you try to narrow down where the differences lie?  For
>example, you
>>could look at the grid functions themselves, including one of
>the evolved
>>variables, one of the ADMBase variables, and also Psi4, to see
>which are
>>actually different.
>
>I'll look at the 1D grid functions now, but
>I wanted to get you this info
>anyway.
>
>Bernard
>
>

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