setunits_8.py
092890f0856dmaster

setunits_8.py
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			#!/usr/bin/env python


			from pNbody import *

			'''
			convert density :

			gear -> g/cm^3 -> atom/cm^3

			'''


			##############################
			# define some system of units
			##############################

			# cgs units (exits in pNbody)
			units.cgs

			# output system of units (the mass units is the hydrogen mass)
			Unit_atom = ctes.PROTONMASS.into(units.cgs)*units.Unit_g
			Unit_atom.set_symbol('atom')
			out_units = units.UnitSystem('local',[units.Unit_cm,Unit_atom,units.Unit_s,units.Unit_K])


			# gear system of units
			params = {}
			params['UnitVelocity_in_cm_per_s'] = 20725573.785998672
			params['UnitMass_in_g'] = 1.989e+43
			params['UnitLength_in_cm'] = 3.085678e+21
			gear_units = units.Set_SystemUnits_From_Params(params)


			##############################
			# now, use to convert
			##############################

			print gear_units.convertionFactorTo(out_units.UnitDensity) # gear to atom/cm^3
			print gear_units.convertionFactorTo(units.cgs.UnitDensity) # gear to g/cm^3
			print 0.1*out_units.convertionFactorTo(units.cgs.UnitDensity) # atom/cm^3 to g/cm^3
			print 0.1*out_units.convertionFactorTo(gear_units.UnitDensity) # atom/cm^3 to gear
			print 1.67e-25*units.cgs.convertionFactorTo(out_units.UnitDensity)