[Yt-svn] yt-commit r858 - trunk/yt/lagos

[britton at wrangler.dreamhost.com]

Author: britton
Date: Fri Oct 31 10:16:02 2008
New Revision: 858
URL: http://yt.spacepope.org/changeset/858

Log:
Added Overdensity field.
Overdensity = ("Density" + "particle_density") / (rho_crit_now * (1+z)^3).
Warning: this field uses particle_density, and thus, requires the cic 
function to be built.

31 October, 2008

Britton Smith



Modified:
   trunk/yt/lagos/DerivedFields.py

Modified: trunk/yt/lagos/DerivedFields.py
==============================================================================
--- trunk/yt/lagos/DerivedFields.py	(original)
+++ trunk/yt/lagos/DerivedFields.py	Fri Oct 31 10:16:02 2008
@@ -51,7 +51,7 @@
 G = 6.67e-8   # cm^3 g^-1 s^-2
 Msun2g = 1.989e33
 MJ_constant = (((5*kboltz)/(G*mh))**(1.5)) * (3/(4*pi))**(0.5) / Msun2g
-
+rho_crit_now = 1.8788e-29 # g cm^-3
 
 class FieldInfoContainer: # We are all Borg.
     _shared_state = {}
@@ -578,6 +578,11 @@
 add_field("NumberDensity", units=r"\rm{cm}^{-3}",
           convert_function=_ConvertNumberDensity)
 
+def Overdensity(field,data):
+    return (data['Density'] + data['particle_density']) / \
+        (rho_crit_now * ((1+data.pf['CosmologyCurrentRedshift'])**3))
+add_field("Overdensity",function=Overdensity,units=r"")
+
 def JeansMassMsun(field,data):
     return (MJ_constant * 
             ((data["Temperature"]/data["MeanMolecularWeight"])**(1.5)) *