[Users] differences in results between two versions of ET

[Yosef Zlochower]

On 07/27/2012 04:21 AM, Ian Hinder wrote:
> Hi Yosef,
>
> I believe the code was reorganised in carpet and this needed the
> algorithm to change in a way that meant numerical results would change.
> I can't check right now, but this should have been mentioned in the
> announcement of the new version of carpet as well as the ET release notes.
>

Thanks. I was surprised that effect of this change was measurable in
the phase at merger (it was of order the differences in phase when
I increased the resolution by a factor of 1.2).

> --
> Ian Hinder
> ian.hinder at aei.mpg.de <mailto:ian.hinder at aei.mpg.de>
>
>
> ----- Original message -----
>  > While trying to understand why the results from a BBH run
>  > differed when using the 2011_05 and 2011_10 version of ET
>  > I noticed that the two versions gave different results on every
>  > other point of the buffer region (in a 2 level run) on the 2nd
>  > time level.
>  >
>  > I reran the test using McLachlan and I found a similar
>  > behavior, but for fewer points (here, only 3, rather
>  > than 8) and only the innermost points.
>  >
>  >
>  > diff -w -u ~/ET/Old/Cactus/test/mc/gxx.x.asc ~/ET/Develop/Cactus/test/mc
>  > | grep "^[+-]2"
>  > -2 0 0 0 0 26 8 8 0.1 1.8 0 0 5.86163790879802
>  > +2 0 0 0 0 26 8 8 0.1 1.8 0 0 5.86163790879801
>  > -2 0 1 0 0 26 8 8 0.1 1.8 0 0 5.86163790879802
>  > +2 0 1 0 0 26 8 8 0.1 1.8 0 0 5.86163790879801
>  > -2 0 1 0 0 59 8 8 0.1 5.1 0 0 2.06954055131151
>  > +2 0 1 0 0 59 8 8 0.1 5.1 0 0 2.06940807802512
>  > -2 0 1 0 0 61 8 8 0.1 5.3 0 0 2.01672019300839
>  > +2 0 1 0 0 61 8 8 0.1 5.3 0 0 2.01674238678588
>  > -2 0 1 0 0 63 8 8 0.1 5.5 0 0 1.96875965038995
>  > +2 0 1 0 0 63 8 8 0.1 5.5 0 0 1.96875664800624
>  >
>  >
>  >