[Commits] [svn:einsteintoolkit] EOS_Omni/trunk/doc/ (Rev. 71)

[cott at tapir.caltech.edu]

User: cott
Date: 2012/12/29 06:57 AM

Added:
 /trunk/doc/
  units.py

Log:
 * add a python script that computes cgs->M_sun=c=G=1 units 
   conversion factors (and their inverses) based on NIST data

File Changes:

Directory: /trunk/doc/
======================

File [added]: units.py
Delta lines: +53 -0
===================================================================
--- trunk/doc/units.py	                        (rev 0)
+++ trunk/doc/units.py	2012-12-29 12:57:38 UTC (rev 71)
@@ -0,0 +1,53 @@
+# Copyright Christian D. Ott, Dec 29, 2012
+# cott at tapir.caltech.edu
+#
+# python script that takes fundamental constants and spits out
+# conversion factors between c = G = M_Sun = 1 and cgs
+
+# constants from NIST table, 2010 data
+# solar mass from http://asa.usno.navy.mil/SecK/2013/Astronomical_Constants_2013.pdf
+
+ggrav = 6.6738480e-8 #cgs
+clite = 2.99792458e10 #cgs
+msun = 1.9884e33 #cgs
+
+print "Using the following constants:"
+print "G: 6.6738480e-8 cm**3 / g / s**2"
+print "c: 2.99792458e10 cm / s"
+print "M_sun: 1.9884e33 g"
+
+print "      mass_gf=%22.14E" % (1.0/msun)
+print "  inv_mass_gf=%22.14E" % msun
+
+# length
+length_gf =  1.0/(ggrav/clite**2 * msun)
+inv_length_gf = 1.0/length_gf
+
+print "    length_gf=%22.14E" % length_gf
+print "inv_length_gf=%22.14E" % inv_length_gf
+
+# density
+rho_gf = 1.0/msun * 1.0/length_gf**3
+inv_rho_gf = 1.0/rho_gf
+
+print "       rho_gf=%22.14E" % rho_gf
+print "   inv_rho_gf=%22.14E" % inv_rho_gf
+
+# time
+time_gf = clite * length_gf
+inv_time_gf = 1.0/time_gf
+print "      time_gf=%22.14E" % time_gf
+print "  inv_time_gf=%22.14E" % inv_time_gf
+
+# specific internal energy erg / gram
+eps_gf = 1.0/clite**2
+inv_eps_gf = clite**2
+print "       eps_gf=%22.14E" % eps_gf
+print "   inv_eps_gf=%22.14E" % inv_eps_gf
+
+# pressure
+press_gf = 1.0/msun * inv_time_gf**2 * inv_length_gf
+inv_press_gf = 1.0/press_gf
+print "     press_gf=%22.14E" % press_gf
+print " inv_press_gf=%22.14E" % inv_press_gf
+