def test09(self):
print "Test add_spin particle attribute, to add rigid body rotation"
numpy.random.seed(123456)
particles = new_plummer_model(1000)
kinetic_energy0 = particles.kinetic_energy()
potential_energy0 = particles.potential_energy(G=nbody_system.G)
particles.position += [3, 0, 2] | nbody_system.length
particles.velocity += [1, 10, 100] | nbody_system.speed
particles.add_spin(3.0 | nbody_system.time**-1)
self.assertAlmostRelativeEquals(particles.center_of_mass(), [3, 0, 2] | nbody_system.length, 12)
self.assertAlmostRelativeEquals(particles.potential_energy(G=nbody_system.G), potential_energy0, 12)
self.assertAlmostRelativeEquals(particles.center_of_mass_velocity(), [1, 10, 100] | nbody_system.speed, 12)
r = particles.position - particles.center_of_mass()
v = particles.velocity - particles.center_of_mass_velocity()
spin_direction = (r).cross(v).mean(axis=0)
spin_direction /= spin_direction.length()
R = r - r*spin_direction
omega = ((R).cross(v) / R.lengths_squared().reshape((-1,1))).mean(axis=0).length()
self.assertAlmostEquals(spin_direction, [0, 0, 1.0], 1)
self.assertAlmostEquals(omega, 3.0 | nbody_system.time**-1, 1)
particles.add_spin([1.0, 0, -3.0] | nbody_system.time**-1)
v = particles.velocity - particles.center_of_mass_velocity()
spin_direction = (r).cross(v).mean(axis=0)
spin_direction /= spin_direction.length()
R = r - r*spin_direction
omega = ((R).cross(v) / R.lengths_squared().reshape((-1,1))).mean(axis=0).length()
self.assertAlmostEquals(omega, 1.0 | nbody_system.time**-1, 1)
def test09(self):
print "Test add_spin particle attribute, to add rigid body rotation"
numpy.random.seed(123456)
particles = new_plummer_model(1000)
kinetic_energy0 = particles.kinetic_energy()
potential_energy0 = particles.potential_energy(G=nbody_system.G)
particles.position += [3, 0, 2] | nbody_system.length
particles.velocity += [1, 10, 100] | nbody_system.speed
particles.add_spin(3.0 | nbody_system.time**-1)
self.assertAlmostRelativeEquals(particles.center_of_mass(), [3, 0, 2] | nbody_system.length, 12)
self.assertAlmostRelativeEquals(particles.potential_energy(G=nbody_system.G), potential_energy0, 12)
self.assertAlmostRelativeEquals(particles.center_of_mass_velocity(), [1, 10, 100] | nbody_system.speed, 12)
r = particles.position - particles.center_of_mass()
v = particles.velocity - particles.center_of_mass_velocity()
spin_direction = (r).cross(v).mean(axis=0)
spin_direction /= spin_direction.length()
R = r - r*spin_direction
omega = ((R).cross(v) / R.lengths_squared().reshape((-1,1))).mean(axis=0).length()
self.assertAlmostEquals(spin_direction, [0, 0, 1.0], 1)
self.assertAlmostEquals(omega, 3.0 | nbody_system.time**-1, 1)
particles.add_spin([1.0, 0, -3.0] | nbody_system.time**-1)
v = particles.velocity - particles.center_of_mass_velocity()
spin_direction = (r).cross(v).mean(axis=0)
spin_direction /= spin_direction.length()
R = r - r*spin_direction
omega = ((R).cross(v) / R.lengths_squared().reshape((-1,1))).mean(axis=0).length()
self.assertAlmostEquals(omega, 1.0 | nbody_system.time**-1, 1)
def test07(self):
particles = new_plummer_model(100)
kinetic_energy0 = particles.kinetic_energy()
potential_energy0 = particles.potential_energy(G=nbody_system.G)
particles.position = rotation.rotated(particles.position, numpy.pi/3, numpy.pi/2, 0.0)
particles.velocity = rotation.rotated(particles.velocity, numpy.pi/3, numpy.pi/2, 0.0)
kinetic_energy1 = particles.kinetic_energy()
potential_energy1 = particles.potential_energy(G=nbody_system.G)
self.assertAlmostRelativeEquals(kinetic_energy1, kinetic_energy0)
self.assertAlmostRelativeEquals(potential_energy1, potential_energy0)
def test07(self):
particles = new_plummer_model(100)
kinetic_energy0 = particles.kinetic_energy()
potential_energy0 = particles.potential_energy(G=nbody_system.G)
particles.position = rotation.rotated(particles.position, numpy.pi/3, numpy.pi/2, 0.0)
particles.velocity = rotation.rotated(particles.velocity, numpy.pi/3, numpy.pi/2, 0.0)
kinetic_energy1 = particles.kinetic_energy()
potential_energy1 = particles.potential_energy(G=nbody_system.G)
self.assertAlmostRelativeEquals(kinetic_energy1, kinetic_energy0)
self.assertAlmostRelativeEquals(potential_energy1, potential_energy0)
def test08(self):
particles = new_plummer_model(100)
kinetic_energy0 = particles.kinetic_energy()
potential_energy0 = particles.potential_energy(G=nbody_system.G)
particles.move_to_center()
particles.position += [3, 0, 2] | nbody_system.length
particles.rotate(numpy.pi/4, numpy.pi/2, 0.0)
self.assertAlmostRelativeEquals(particles.center_of_mass(),
[numpy.sqrt(2), -numpy.sqrt(2), -3] | nbody_system.length, 7)
kinetic_energy1 = particles.kinetic_energy()
potential_energy1 = particles.potential_energy(G=nbody_system.G)
self.assertAlmostRelativeEquals(kinetic_energy1, kinetic_energy0)
self.assertAlmostRelativeEquals(potential_energy1, potential_energy0)
def test08(self):
particles = new_plummer_model(100)
kinetic_energy0 = particles.kinetic_energy()
potential_energy0 = particles.potential_energy(G=nbody_system.G)
particles.move_to_center()
particles.position += [3, 0, 2] | nbody_system.length
particles.rotate(numpy.pi/4, numpy.pi/2, 0.0)
self.assertAlmostRelativeEquals(particles.center_of_mass(),
[numpy.sqrt(2), -numpy.sqrt(2), -3] | nbody_system.length, 7)
kinetic_energy1 = particles.kinetic_energy()
potential_energy1 = particles.potential_energy(G=nbody_system.G)
self.assertAlmostRelativeEquals(kinetic_energy1, kinetic_energy0)
self.assertAlmostRelativeEquals(potential_energy1, potential_energy0)