[yt-users] Halo positions in merger trees

Jean-Claude Waizmann waizmann at ita.uni-heidelberg.de
Thu Aug 6 09:04:23 PDT 2009


Unfortunately, that is terrible news and explains the difference in the
number of particles that are found. So we will now see what we can do
about it.

Thanks very much, so we know what's the problem.

-Jean-Claude

Am Donnerstag, den 06.08.2009, 08:49 -0700 schrieb Stephen Skory:
> Jean-Claude,
> 
> 
> > You guessed right, no stars involved. Indeed I used the positions for
> > the densest particle, however the center of mass does not differ too
> > much from it. So the positions are still not consistent. Furthermore
> > there is a significant difference in the number of particles, between
> > the two codes for the same threshold.
> 
> Can you send me the code you used to drive yt, as in the python script you built with fastBuildMerge.py? I'll edit it and send it back to you and ask you to run it on your dataset.
> 
> > Maybe I should mention, that I run the code on enzo-1.0-like outputs, so
> > I changed the file handling in the beginning of fastBuildMerge.py, but
> > this should not interfere with the algorithm, however I will check this.
> 
> This may be a problem for you, unrelated to the HOP problem. There is a bug in enzo 1.0 that affects the merger tree code. The merger tree relies on the particles having unique IDs, and enzo 1.0 generally does not keep unique particle IDs if it is run in parallel. This bug has been fixed in enzo 1.5. I hope this isn't terrible news for you!
> 
>  _______________________________________________________
> sskory at physics.ucsd.edu           o__  Stephen Skory
> http://physics.ucsd.edu/~sskory/ _.>/ _Graduate Student
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