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Fri, Jun 21, 04:45

gget_ctes
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#!/usr/bin/env python
'''
Get some constantes in user units (from a user units defined unity system)
Yves Revaz
Thu Feb 16 15:06:07 CET 2006
'''
from numarray import *
try:
from optparse import OptionParser
except ImportError:
from optik import OptionParser
def parse_options():
usage = "usage: %prog [options] file"
parser = OptionParser(usage=usage)
parser.add_option("--UnitLength_in_cm",
action="store",
dest="UnitLength_in_cm",
type="float",
default=0,
help="UnitLength in cm")
parser.add_option("--UnitMass_in_g",
action="store",
dest="UnitMass_in_g",
type="float",
default=0,
help="UnitMass in g")
parser.add_option("--UnitVelocity_in_cm_per_s",
action="store",
dest="UnitVelocity_in_cm_per_s",
type="float",
default=0,
help="UnitVelocity in cm per s")
parser.add_option("--HydrogenMassFraction",
action="store",
dest="HydrogenMassFraction",
type="float",
default=0.76,
help="Hydrogen Mass Fraction")
(options, args) = parser.parse_args()
if options.UnitLength_in_cm == 0:
print "you must specify UnitLength_in_cm"
sys.exit(0)
if options.UnitMass_in_g == 0:
print "you must specify UnitMass_in_g"
sys.exit(0)
if options.UnitVelocity_in_cm_per_s == 0:
print "you must specify UnitVelocity_in_cm_per_s"
sys.exit(0)
return options
#############################
# main
#############################
BOLTZMANN = 1.3806e-16
PROTONMASS = 1.6726e-24
# get options
options = parse_options()
UnitLength_in_cm = options.UnitLength_in_cm
UnitMass_in_g = options.UnitMass_in_g
UnitVelocity_in_cm_per_s = options.UnitVelocity_in_cm_per_s
HydrogenMassFraction = options.HydrogenMassFraction
UnitTime_in_s = UnitLength_in_cm / UnitVelocity_in_cm_per_s;
UnitDensity_in_cgs = UnitMass_in_g / pow(UnitLength_in_cm, 3);
UnitPressure_in_cgs = UnitMass_in_g / UnitLength_in_cm / pow(UnitTime_in_s, 2);
UnitCoolingRate_in_cgs = UnitPressure_in_cgs / UnitTime_in_s;
UnitEnergy_in_cgs = UnitMass_in_g * pow(UnitLength_in_cm, 2) / pow(UnitTime_in_s, 2);
meanweight = 4.0 / (1 + 3 * HydrogenMassFraction)
Boltzmann = BOLTZMANN /UnitEnergy_in_cgs
ProtonMass = PROTONMASS/UnitMass_in_g
mumh = ProtonMass*meanweight
print "Boltzmann = %g"%Boltzmann
print "mumh = %g"%mumh
print "X = %4.2f"%HydrogenMassFraction

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