def test_euler(self):
"""Test used to check that Euler's method works appropiatley.
"""
planetA = CelestialBody("B",1,1,1,"Planet",1,10000,"blue")
star = CelestialBody("A",1,1,1,"Star",0,10000,"blue")
planetB = CelestialBody("B",1,2,1,"Planet",1,10000,"blue")
planetB.position = np.array([-1.0,0.0])
planetB.velocity = np.array([0.0,-planetA.velocity[1]])
system = SolarSystem(3600,1000,Options.NORMAL_RUN,"CelestialObjects")
system.celestial_bodies = [star,planetA,planetB]
system.update_initial_acceleration()
for i in range(100):
system.update_euler()
self.assertEqual(0.0,star.acceleration[0])
self.assertEqual(0.0,star.acceleration[1])
def energy_graph_comparisson(updates):
"""Function used to generate a comparison graph between Euler's method and Beeman's
to show conservation (or not conservation) of energy in both methods
"""
system = SolarSystem(3600, 10.175 * 10**3, Options.NORMAL_RUN,
"CelestialObjects")
energy_1 = [system.get_energy()]
system2 = SolarSystem(3600, 10.175 * 10**3, Options.NORMAL_RUN,
"CelestialObjects")
energy_2 = [system2.get_energy()]
iterate = updates
iterations = [i * 3600 for i in range(iterate + 1)]
for i in range(iterate):
energy_1.append(system.update_beeman())
energy_2.append(system2.update_euler())
plt.xlabel('time(s)')
plt.ylabel('Energy [J]')
plt.plot(iterations, energy_1, iterations, energy_2)
plt.show()