def test15(self): particles = datamodel.Particles(2) particles.x = [0.0,10.0] | nbody_system.length particles.y = 0.0 | nbody_system.length particles.z = 0.0 | nbody_system.length particles.vx = 0.0 | nbody_system.speed particles.vy = 0.0 | nbody_system.speed particles.vz = 0.0 | nbody_system.speed particles.mass = 1.0 | nbody_system.mass instance = Hermite() instance.particles.add_particles(particles) instance.commit_particles() self.assertEqual(instance.particles[0].radius, 0.0 | nbody_system.length) p = datamodel.Particle( x=1.0 | nbody_system.length, y=2.0 | nbody_system.length, z=3.0 | nbody_system.length, vx=1.0 | nbody_system.speed, vy=2.0 | nbody_system.speed, vz=3.0 | nbody_system.speed, mass=1.0 | nbody_system.mass, radius=4.0 | nbody_system.length, ) instance.particles.add_particle(p) self.assertEqual(instance.particles[0].radius, 0.0 | nbody_system.length) self.assertEqual(instance.particles[1].radius, 0.0 | nbody_system.length) self.assertEqual(instance.particles[2].radius, 4.0 | nbody_system.length) instance.stop()
def test18(self): particles = datamodel.Particles(2) particles.x = [0.0,1.0] | nbody_system.length particles.y = 0.0 | nbody_system.length particles.z = 0.0 | nbody_system.length particles.vx = 0.0 | nbody_system.speed particles.vy = 0.0 | nbody_system.speed particles.vz = 0.0 | nbody_system.speed particles.mass = 1.0 | nbody_system.mass instance = Hermite() instance.particles.add_particles(particles) instance.commit_particles() self.assertEqual(instance.particles[0].radius, 0.0 | nbody_system.length) instance.parameters.end_time_accuracy_factor = 1.0 instance.evolve_model(0.1 | nbody_system.time) self.assertAlmostRelativeEquals(instance.model_time, 0.10563767746 |nbody_system.time, 5) instance.parameters.end_time_accuracy_factor = -1.0 instance.evolve_model(0.3 | nbody_system.time) self.assertAlmostRelativeEquals(instance.model_time, 0.266758127609 |nbody_system.time, 5) instance.parameters.end_time_accuracy_factor = 0.0 instance.evolve_model(0.4 | nbody_system.time) self.assertAlmostRelativeEquals(instance.model_time, 0.4 |nbody_system.time, 6) instance.parameters.end_time_accuracy_factor = -0.5 instance.evolve_model(0.5 | nbody_system.time) self.assertAlmostRelativeEquals(instance.model_time, 0.48974930698 |nbody_system.time, 6) instance.parameters.end_time_accuracy_factor = +0.5 instance.evolve_model(0.6 | nbody_system.time) self.assertAlmostRelativeEquals(instance.model_time, 0.6042733579 |nbody_system.time, 6) instance.stop()
def test19(self): particles = datamodel.Particles(2) particles.x = [0.0,200.0] | nbody_system.length particles.y = 0.0 | nbody_system.length particles.z = 0.0 | nbody_system.length particles.vx = 0.0 | nbody_system.speed particles.vy = 0.0 | nbody_system.speed particles.vz = 0.0 | nbody_system.speed particles.mass = 1.0 | nbody_system.mass instance = Hermite() instance.particles.add_particles(particles) instance.commit_particles() self.assertEqual(instance.particles[0].radius, 0.0 | nbody_system.length) instance.parameters.end_time_accuracy_factor = 0.0 instance.evolve_model(0.1 | nbody_system.time) self.assertAlmostRelativeEquals(instance.model_time, 0.1 |nbody_system.time, 5) instance.stop()
def test7(self): print("Test7: Testing effect of Hermite parameter epsilon_squared") convert_nbody = nbody_system.nbody_to_si(1.0 | units.MSun, 1.0 | units.AU) particles = datamodel.Particles(2) sun = particles[0] sun.mass = 1.0 | units.MSun sun.position = [0.0, 0.0, 0.0] | units.AU sun.velocity = [0.0, 0.0, 0.0] | units.AU / units.yr sun.radius = 1.0 | units.RSun earth = particles[1] earth.mass = 5.9736e24 | units.kg earth.radius = 6371.0 | units.km earth.position = [0.0, 1.0, 0.0] | units.AU earth.velocity = [2.0 * numpy.pi, -0.0001, 0.0] | units.AU / units.yr initial_direction = math.atan((earth.velocity[0] / earth.velocity[1])) final_direction = [] for log_eps2 in range(-9, 10, 2): instance = Hermite(convert_nbody) instance.parameters.end_time_accuracy_factor = 0.0 instance.parameters.epsilon_squared = 10.0**log_eps2 | units.AU**2 instance.particles.add_particles(particles) instance.commit_particles() instance.evolve_model(0.25 | units.yr) final_direction.append( math.atan((instance.particles[1].velocity[0] / instance.particles[1].velocity[1]))) instance.stop() # Small values of epsilon_squared should result in normal earth-sun dynamics: rotation of 90 degrees self.assertAlmostEqual(abs(final_direction[0]), abs(initial_direction + math.pi / 2.0), 2) # Large values of epsilon_squared should result in ~ no interaction self.assertAlmostEqual(final_direction[-1], initial_direction, 2) # Outcome is most sensitive to epsilon_squared when epsilon_squared = d(earth, sun)^2 delta = [ abs(final_direction[i + 1] - final_direction[i]) for i in range(len(final_direction) - 1) ] self.assertEqual(delta[len(final_direction) // 2 - 1], max(delta))
def new_star_code_hermite(self): result = Hermite() result.parameters.epsilon_squared = self.star_epsilon**2 result.particles.add_particles(self.new_particles_cluster()) result.commit_particles() return result