[yt-users] Halo positions in merger trees

[Jean-Claude Waizmann]

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.

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.



Am Donnerstag, den 06.08.2009, 08:06 -0700 schrieb Stephen Skory:
> Jean-Claude,
> 
> 
> > sphere = pf.h.sphere([0.5 0.5 0.5],1.0)
> > hop_results = lagos.hop.HopList(sphere, 80.000000)
> > 
> > which I copied from the merger code, so the thresholds were the same,
> > unfortunately.
> 
> Darn it. Another simple question is (and I'm guessing 'no' is the answer), are there stars in your simulation? If yes, did you do all the runs of HOP with them considered (or excluded)?
> 
> Are you comparing the same columns of the output of HOP? Are you sure you're not comparing the most-dense particle position to the calculated center of mass? In the text file output of HOP, the first columns of positions are the most-dense particle, while the merger tree should be using the center of mass (unless I've done something wrong!).
> 
> I'm thinking of what else could be going on...
> 
>  _______________________________________________________
> sskory at physics.ucsd.edu           o__  Stephen Skory
> http://physics.ucsd.edu/~sskory/ _.>/ _Graduate Student
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