[yt-users] Halo positions in merger trees

[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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