[Yt-svn] yt-commit r1216 - trunk/yt/lagos/fof

[sskory at wrangler.dreamhost.com]

Author: sskory
Date: Mon Mar 16 12:57:06 2009
New Revision: 1216
URL: http://yt.spacepope.org/changeset/1216

Log:
another revision to center_of_mass(), now parallel-fof is nearly identical to serial. I think the remaining issues have to do with periodicity and whether or not the fof code is respecting it or not. But this is quite close.

Modified:
   trunk/yt/lagos/fof/FOF_Output.py

Modified: trunk/yt/lagos/fof/FOF_Output.py
==============================================================================
--- trunk/yt/lagos/fof/FOF_Output.py	(original)
+++ trunk/yt/lagos/fof/FOF_Output.py	Mon Mar 16 12:57:06 2009
@@ -162,22 +162,15 @@
         """
         Calculate and return the center of mass.
         """
-        c_vec = na.array([0.,0.,0.])
         pm = self["ParticleMassMsun"]
         cx = self["particle_position_x"]
         cy = self["particle_position_y"]
         cz = self["particle_position_z"]
-        dx = max(cx) - min(cx)
-        dy = max(cy) - min(cy)
-        dz = max(cz) - min(cz)
-        if dx>0.5: c_vec[0] = 0.5
-        if dy>0.5: c_vec[1] = 0.5
-        if dz>0.5: c_vec[2] = 0.5
-        cx = (cx - c_vec[0])
-        cy = (cy - c_vec[1])
-        cz = (cz - c_vec[2])
+        c_vec = na.array([cx[0],cy[0],cz[0]]) - na.array([0.5,0.5,0.5])
+        cx = cx - c_vec[0]
+        cy = cy - c_vec[1]
+        cz = cz - c_vec[2]
         com = na.array([v-na.floor(v) for v in [cx,cy,cz]])
-        com = (pm * com).sum(axis=1)/pm.sum() + c_vec
         return com
 
     def total_mass(self):