[Yt-dev] errors in SpecificAngularMomentum

[John Wise]

Hi all,

I was trying to calculate the spin parameter for a halo with the following simple script,

center = [0.495013,     0.494046,     0.495160]
radius = 100  # pc
pf = load("DD0019/output_0019")
sp = pf.h.sphere(center, radius/pf["pc"])
gas_spin = sp.quantities["BaryonSpinParameter"]()

and it doesn't work in parallel.  It gives the following traceback.

---
Traceback (most recent call last):
  File "spin.py", line 9, in <module>
    gas_spin = sp.quantities["BaryonSpinParameter"]()
  File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/yt-2.1dev-py2.6-macosx-10.6-intel.egg/yt/data_objects/derived_quantities.py", line 85, in __call__
    self.func(e, *args, **kwargs)
  File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/yt-2.1dev-py2.6-macosx-10.6-intel.egg/yt/data_objects/derived_quantities.py", line 237, in _BaryonSpinParameter
    am = data["SpecificAngularMomentum"]*data["CellMassMsun"]
ValueError: shape mismatch: objects cannot be broadcast to a single shape
Traceback (most recent call last):
  File "spin.py", line 9, in <module>
    gas_spin = sp.quantities["BaryonSpinParameter"]()
  File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/yt-2.1dev-py2.6-macosx-10.6-intel.egg/yt/data_objects/derived_quantities.py", line 85, in __call__
    self.func(e, *args, **kwargs)
  File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/yt-2.1dev-py2.6-macosx-10.6-intel.egg/yt/data_objects/derived_quantities.py", line 237, in _BaryonSpinParameter
    am = data["SpecificAngularMomentum"]*data["CellMassMsun"]
ValueError: shape mismatch: objects cannot be broadcast to a single shape
---


This happens on multiple systems.  I looked into this further, and I think the shapes of the angular momentum data are not being preserved in the MPI calls.  Also the shapes appear wrong in a serial calculation.  In serial, everything looks fine until data["SpecificAngularMomentum"] is returned.  Here are the shapes of the arrays.

v_vec: (3,16,16,16)
cross product of r_vec and v_vec: (3,16,16,16)
and the returned array from _SpecificAngularMomentum has a shape of (3,0)!

Then when I try to run it with 2 processors, the shapes change to
v_vec: (3,4096)
cross: (3,4096)
_SpecificAngularMomentum result: (12288,)

Can someone replicate this error?  Any ideas?

Thanks,
John