elif opt == '-y':
log_y = True
# Check for mandatory arguments.
if index == None:
print 'Error: No polytropic index supplied!'
sys.exit(1)
if nsteps == None:
print 'Error: No step number supplied!'
sys.exit(1)
# Initialize the polytrope.
rho_0 = 150.0
pressure_0 = 10**17.369
radius = 6.95508e10
star = Polytrope(nsteps, index, rho_0, pressure_0, radius)
# Run the solver and plot the results.
indices = range(1, index+1) + [1.5]
indices.sort()
for index in indices:
star.update_index(index)
star.rk4_outward()
radpts = star.radpts / star.radius
density = star.density / star.rho_0
plot_label = r'$n = ' + str(index) + '$'
plt.plot(radpts, density, label=plot_label)
axes = plt.axes()
plt.xlabel(r'$R / R_*$')
plt.ylabel(r'$\rho / \rho_c$')
elif opt == '-y':
log_y = True
# Check for mandatory arguments.
if index == None:
print 'Error: No polytropic index supplied!'
sys.exit(1)
if nsteps == None:
print 'Error: No step number supplied!'
sys.exit(1)
# Initialize the polytrope.
rho_0 = 150.0
pressure_0 = 10**17.369
radius = 6.95508e10
star = Polytrope(nsteps, index, rho_0, pressure_0, radius)
# Run the solver and plot the results.
star.rk4_outward()
radpts = star.radpts / star.radius
density = star.density / star.rho_0
# Plot the results.
axes = plt.axes()
plt.plot(radpts, density, label='Numerical solution')
plt.xlabel(r'$R / R_*$')
plt.ylabel(r'$\rho / \rho_c$')
if star.index == int(star.index):
plt.title(r'$n = ' + str(int(star.index)) + '$')
else:
plt.title(r'$n = ' + str(star.index) + '$')
