def test2(self):
print "Testing MI6 parameters"
instance = MI6(self.default_converter, **default_options)
instance.initialize_code()
self.assertEquals(
instance.parameters.epsilon_squared,
instance.unit_converter.to_si(0.0 | nbody_system.length**2))
self.assertEquals(instance.parameters.timestep_parameter, 0.1)
for par, value in [
('epsilon_squared_star_star', 0.0 | nbody_system.length**2),
('epsilon_squared_star_blackhole', 0.0 | nbody_system.length**2),
('epsilon_squared_blackhole_blackhole',
0.0 | nbody_system.length**2),
('initial_timestep_parameter', 1.0e-4),
('timestep_parameter_stars', 0.1),
('timestep_parameter_supermassive_black_holes', 0.4),
('timestep_parameter_intermediate_mass_black_holes', 0.4),
('max_relative_energy_error', 5.0e-5),
('maximum_timestep', 1.0 / 1024.0 | nbody_system.time),
('smbh_mass', 1.0 | nbody_system.mass),
('lightspeed', 1.0 | nbody_system.speed)
]:
self.assertEquals(instance.unit_converter.to_si(value),
getattr(instance.parameters, par))
if hasattr(value, 'unit'):
new_value = 3.0 | value.unit
else:
new_value = 3.0
setattr(instance.parameters, par, new_value)
self.assertEquals(instance.unit_converter.to_si(new_value),
getattr(instance.parameters, par))
# epsilon_squared is an alias for epsilon_squared_star_star, so epsilon_squared also has become 3:
self.assertEquals(
instance.parameters.epsilon_squared,
instance.unit_converter.to_si(3.0 | nbody_system.length**2))
instance.parameters.epsilon_squared = 0.1 | nbody_system.length**2
self.assertEquals(
instance.parameters.epsilon_squared,
instance.unit_converter.to_si(0.1 | nbody_system.length**2))
# timestep_parameter is an alias for timestep_parameter_stars, so timestep_parameter also has become 3:
self.assertEquals(instance.parameters.timestep_parameter, 3.0)
instance.parameters.timestep_parameter = 0.01
self.assertEquals(instance.parameters.timestep_parameter, 0.01)
self.assertEquals(instance.parameters.include_smbh, False)
instance.parameters.include_smbh = True
self.assertEquals(instance.parameters.include_smbh, True)
self.assertEquals(instance.parameters.calculate_postnewtonian, True)
instance.parameters.calculate_postnewtonian = False
self.assertEquals(instance.parameters.calculate_postnewtonian, False)
self.assertEquals(instance.parameters.drink,
"Vodka martini. Shaken, not stirred.")
instance.stop()
def test9(self):
print "Testing MI6 evolve_model and getters energy, plummer sphere, no SMBH"
converter = nbody_system.nbody_to_si(1.0e2 | units.MSun,
1.0 | units.parsec)
instance = MI6(converter, **default_options)
instance.initialize_code()
instance.parameters.smbh_mass = 0.0 | units.MSun
instance.commit_parameters()
numpy.random.seed(987654321)
instance.particles.add_particles(
new_plummer_model(100, convert_nbody=converter))
instance.commit_particles()
kinetic_energy = instance.kinetic_energy
potential_energy = instance.potential_energy
self.assertAlmostRelativeEqual(kinetic_energy,
2.12292810174e+37 | units.J, 10)
self.assertAlmostRelativeEqual(potential_energy,
-4.33511391248e+37 | units.J, 10)
initial_total_energy = kinetic_energy + potential_energy
instance.evolve_model(0.1 | nbody_system.time)
kinetic_energy = instance.kinetic_energy
potential_energy = instance.potential_energy
self.assertAlmostRelativeEqual(kinetic_energy,
2.13633848369e+37 | units.J, 5)
self.assertAlmostRelativeEqual(potential_energy,
-4.34851806763e+37 | units.J, 5)
self.assertAlmostRelativeEqual(potential_energy + kinetic_energy,
initial_total_energy, 5)
instance.cleanup_code()
instance.stop()
def test7(self):
print "Testing effect of MI6 parameter epsilon_squared"
converter = nbody_system.nbody_to_si(1.0 | units.MSun, 1.0 | units.AU)
particles = self.new_sun_earth_system()
particles.rotate(0.0, 0.0, -math.pi / 4)
particles.move_to_center()
tan_initial_direction = particles[1].vy / particles[1].vx
self.assertAlmostEquals(tan_initial_direction, math.tan(math.pi / 4))
tan_final_direction = []
for log_eps2 in range(-9, 10, 2):
instance = MI6(converter, **default_options)
instance.initialize_code()
instance.parameters.epsilon_squared = 10.0**log_eps2 | units.AU**2
instance.parameters.smbh_mass = 0.0 | units.MSun
instance.commit_parameters()
instance.particles.add_particles(particles)
instance.commit_particles()
instance.evolve_model(0.25 | units.yr)
tan_final_direction.append(instance.particles[1].velocity[1] /
instance.particles[1].velocity[0])
instance.cleanup_code()
instance.stop()
# Small values of epsilon_squared should result in normal earth-sun dynamics: rotation of 90 degrees
self.assertAlmostEquals(tan_final_direction[0],
math.tan(3 * math.pi / 4.0), 2)
# Large values of epsilon_squared should result in ~ no interaction
self.assertAlmostEquals(tan_final_direction[-1], tan_initial_direction,
2)
# Outcome is most sensitive to epsilon_squared when epsilon_squared = d(earth, sun)^2
delta = [
abs(tan_final_direction[i + 1] - tan_final_direction[i])
for i in range(len(tan_final_direction) - 1)
]
self.assertEquals(delta[len(tan_final_direction) // 2 - 1], max(delta))
def test1(self):
print "Testing MI6 initialization"
instance = MI6(self.default_converter, **default_options)
instance.initialize_code()
instance.commit_parameters()
instance.cleanup_code()
instance.stop()
def new_coupled_system(hydro, binary_system, t_end, n_steps):
kick_from_hydro = CalculateFieldForParticles(particles=hydro.particles, gravity_constant=constants.G)
kick_from_hydro.smoothing_length_squared = 100 | units.RSun**2
unit_converter = nbody_system.nbody_to_si(binary_system.particles.total_mass(), t_end)
kicker_code = MI6(unit_converter, redirection='file', redirect_file='kicker_code_mi6_out.log')
kicker_code.parameters.epsilon_squared = 100 | units.RSun**2
kick_from_binary = CalculateFieldForCodesUsingReinitialize(kicker_code, (binary_system,))
coupled_system = Bridge(timestep=(t_end / (2 * n_steps)), verbose=False, use_threading=True)
coupled_system.add_system(binary_system, (kick_from_hydro,), False)
coupled_system.add_system(hydro, (kick_from_binary,), False)
return coupled_system
def test8(self):
print "Testing MI6 get_gravity_at_point and get_potential_at_point"
instance = MI6(**default_options)
instance.initialize_code()
instance.parameters.epsilon_squared = 0.0 | nbody_system.length**2
instance.parameters.smbh_mass = 0.0 | nbody_system.mass
particles = Particles(2)
particles.mass = 1.0 | nbody_system.mass
particles.radius = 0.0 | nbody_system.length
particles.position = [[0.0, 0.0, 0.0], [2.0, 0.0, 0.0]
] | nbody_system.length
particles.velocity = [[0.0, 0.0, 0.0], [0.0, 0.0, 0.0]
] | nbody_system.speed
instance.particles.add_particles(particles)
zero = 0.0 | nbody_system.length
fx, fy, fz = instance.get_gravity_at_point(zero,
1.0 | nbody_system.length,
zero, zero)
self.assertAlmostEqual(fx, 0.0 | nbody_system.acceleration)
self.assertAlmostEqual(fy, 0.0 | nbody_system.acceleration)
self.assertAlmostEqual(fz, 0.0 | nbody_system.acceleration)
for x in (0.25, 0.5, 0.75):
x0 = x | nbody_system.length
x1 = (2.0 - x) | nbody_system.length
potential0 = instance.get_potential_at_point(zero, x0, zero, zero)
potential1 = instance.get_potential_at_point(zero, x1, zero, zero)
fx0, fy0, fz0 = instance.get_gravity_at_point(zero, x0, zero, zero)
fx1, fy1, fz1 = instance.get_gravity_at_point(zero, x1, zero, zero)
self.assertAlmostEqual(fy0, 0.0 | nbody_system.acceleration)
self.assertAlmostEqual(fz0, 0.0 | nbody_system.acceleration)
self.assertAlmostEqual(fy1, 0.0 | nbody_system.acceleration)
self.assertAlmostEqual(fz1, 0.0 | nbody_system.acceleration)
self.assertAlmostEqual(fx0, -1.0 * fx1)
fx = (-1.0 / (x0**2) + 1.0 /
(x1**2)) * (1.0
| nbody_system.length**3 / nbody_system.time**2)
self.assertAlmostEqual(fx, fx0)
self.assertAlmostEqual(potential0, potential1)
instance.stop()
def test11(self):
print "Testing MI6 properties"
numpy.random.seed(12345)
particles = new_plummer_model(100, do_scale=True)
particles.position += [1, 2, 3] | nbody_system.length
cluster_velocity = [4, 5, 6] | nbody_system.speed
particles.velocity += cluster_velocity
external_kinetic_energy = (
0.5 | nbody_system.mass) * cluster_velocity.length_squared()
instance = MI6(**default_options)
instance.particles.add_particles(particles)
kinetic_energy = instance.kinetic_energy - external_kinetic_energy
potential_energy = instance.potential_energy
self.assertAlmostRelativeEqual(kinetic_energy,
0.25 | nbody_system.energy, 10)
self.assertAlmostRelativeEqual(potential_energy,
-0.5 | nbody_system.energy, 10)
self.assertAlmostRelativeEqual(instance.total_mass,
1.0 | nbody_system.mass, 10)
self.assertAlmostRelativeEqual(instance.center_of_mass_position,
[1, 2, 3] | nbody_system.length, 10)
self.assertAlmostRelativeEqual(instance.center_of_mass_velocity,
[4, 5, 6] | nbody_system.speed, 10)
initial_total_energy = kinetic_energy + potential_energy
instance.evolve_model(0.1 | nbody_system.time)
self.assertAlmostRelativeEqual(instance.model_time,
0.1 | nbody_system.time)
kinetic_energy = instance.kinetic_energy - external_kinetic_energy
potential_energy = instance.potential_energy
self.assertAlmostRelativeEqual(kinetic_energy + potential_energy,
-0.25 | nbody_system.energy, 3)
self.assertAlmostRelativeEqual(instance.total_mass,
1.0 | nbody_system.mass, 3)
self.assertAlmostRelativeEqual(instance.center_of_mass_position,
[1.4, 2.5, 3.6] | nbody_system.length,
3)
self.assertAlmostRelativeEqual(instance.center_of_mass_velocity,
[4, 5, 6] | nbody_system.speed, 3)
instance.cleanup_code()
instance.stop()
def test3(self):
print "Testing MI6 particles"
instance = MI6(self.default_converter, **default_options)
instance.initialize_code()
instance.commit_parameters()
instance.particles.add_particles(self.new_sun_earth_system())
instance.commit_particles()
self.assertAlmostEquals(instance.particles.mass,
[1.0, 3.0037e-6] | units.MSun)
self.assertAlmostEquals(instance.particles.radius, 1.0 | units.RSun)
self.assertAlmostEquals(instance.particles.position,
[[0.0, 0.0, 0.0], [1.0, 0.0, 0.0]] | units.AU)
self.assertAlmostEquals(instance.particles.velocity,
[[0.0, 0.0, 0.0], [0.0, 29.7885, 0.0]]
| units.km / units.s, 3)
instance.cleanup_code()
instance.stop()
def test4(self):
print "Testing MI6 evolve_model, 2 particles orbiting the SMBH"
particles = Particles(2)
particles.mass = 1.0 | units.MSun
particles.radius = 1.0 | units.RSun
particles.position = [[0.0, 0.0, 0.0], [2.0, 0.0, 0.0]] | units.AU
particles.velocity = [[0.0, 0.0, 0.0], [0.0, 0.0, 0.0]
] | units.km / units.s
particles[1].vy = ((constants.G * (10001.0 | units.MSun) /
(1.0 | units.AU)).sqrt() +
(constants.G * (10000.0 | units.MSun) /
(1.0 | units.AU)).sqrt())
particles.move_to_center()
print particles
instance = MI6(self.default_converter, **default_options)
instance.initialize_code()
instance.parameters.include_smbh = True
instance.parameters.lightspeed = constants.c
instance.commit_parameters()
instance.particles.add_particles(particles)
instance.commit_particles()
primary = instance.particles[0]
P = 2 * math.pi * primary.x / primary.vy
P_corrected = (P) * (2.0 / (1.0 + math.sqrt(1.0001)))
position_at_start = primary.position.x
instance.evolve_model(P_corrected / 4.0)
self.assertAlmostRelativeEqual(position_at_start, primary.position.y,
3)
instance.evolve_model(P_corrected / 2.0)
self.assertAlmostRelativeEqual(position_at_start, -primary.position.x,
3)
instance.evolve_model(P_corrected)
self.assertAlmostRelativeEqual(position_at_start, primary.position.x,
3)
instance.cleanup_code()
instance.stop()
def test5(self):
print "Testing MI6 evolve_model, 2 particles, no SMBH"
particles = Particles(2)
particles.mass = 1.0 | units.MSun
particles.radius = 1.0 | units.RSun
particles.position = [[0.0, 0.0, 0.0], [2.0, 0.0, 0.0]] | units.AU
particles.velocity = [[0.0, 0.0, 0.0], [0.0, 0.0, 0.0]
] | units.km / units.s
particles[1].vy = (constants.G * (2.0 | units.MSun) /
(2.0 | units.AU)).sqrt()
particles.move_to_center()
print particles
converter = nbody_system.nbody_to_si(1.0 | units.MSun, 1.0 | units.AU)
instance = MI6(converter, **default_options)
instance.initialize_code()
instance.parameters.smbh_mass = 0.0 | units.MSun
instance.commit_parameters()
instance.particles.add_particles(particles)
instance.commit_particles()
primary = instance.particles[0]
P = 2 * math.pi * primary.x / primary.vy
position_at_start = primary.position.x
instance.evolve_model(P / 4.0)
self.assertAlmostRelativeEqual(position_at_start, primary.position.y,
3)
instance.evolve_model(P / 2.0)
self.assertAlmostRelativeEqual(position_at_start, -primary.position.x,
3)
instance.evolve_model(P)
self.assertAlmostRelativeEqual(position_at_start, primary.position.x,
3)
instance.cleanup_code()
instance.stop()
def test6(self):
print "Testing MI6 evolve_model, earth-sun system, no SMBH"
converter = nbody_system.nbody_to_si(1.0 | units.MSun, 1.0 | units.AU)
instance = MI6(converter, **default_options)
instance.initialize_code()
instance.parameters.smbh_mass = 0.0 | units.MSun
instance.commit_parameters()
instance.particles.add_particles(self.new_sun_earth_system())
instance.commit_particles()
earth = instance.particles[1]
position_at_start = earth.position.x
instance.evolve_model(0.25 | units.yr)
self.assertAlmostRelativeEqual(position_at_start, earth.position.y, 3)
instance.evolve_model(0.5 | units.yr)
self.assertAlmostRelativeEqual(position_at_start, -earth.position.x, 3)
instance.evolve_model(1.0 | units.yr)
self.assertAlmostRelativeEqual(position_at_start, earth.position.x, 3)
instance.cleanup_code()
instance.stop()
def test10(self):
print "Testing MI6 collision_detection"
particles = Particles(7)
particles.mass = 0.00000001 | nbody_system.mass
particles.radius = 0.0001 | nbody_system.length
particles.x = [-101.0, -100.0, -0.5, 0.5, 100.0, 101.0, 104.0
] | nbody_system.length
particles.y = 0 | nbody_system.length
particles.z = 0 | nbody_system.length
particles.velocity = [[2, 0, 0], [-2, 0, 0]
] * 3 + [[-4, 0, 0]] | nbody_system.speed
instance = MI6(**default_options)
instance.initialize_code()
instance.parameters.set_defaults()
instance.particles.add_particles(particles)
collisions = instance.stopping_conditions.collision_detection
collisions.enable()
instance.evolve_model(1.0 | nbody_system.time)
self.assertTrue(collisions.is_set())
self.assertAlmostEquals(
instance.model_time, -(particles[0].x - particles[1].x) /
(particles[0].vx - particles[1].vx), 3)
self.assertEquals(len(collisions.particles(0)), 3)
self.assertEquals(len(collisions.particles(1)), 3)
self.assertEquals(
len(particles - collisions.particles(0) - collisions.particles(1)),
1)
self.assertEquals(
abs(collisions.particles(0).x - collisions.particles(1).x) <
(collisions.particles(0).radius + collisions.particles(1).radius),
[True, True, True])
sticky_merged = Particles(len(collisions.particles(0)))
sticky_merged.mass = collisions.particles(
0).mass + collisions.particles(1).mass
sticky_merged.radius = collisions.particles(0).radius
for p1, p2, merged in zip(collisions.particles(0),
collisions.particles(1), sticky_merged):
merged.position = (p1 + p2).center_of_mass()
merged.velocity = (p1 + p2).center_of_mass_velocity()
print instance.model_time
print instance.particles
instance.particles.remove_particles(
collisions.particles(0) + collisions.particles(1))
instance.particles.add_particles(sticky_merged)
instance.evolve_model(1.0 | nbody_system.time)
print
print instance.model_time
print instance.particles
self.assertTrue(collisions.is_set())
self.assertAlmostEquals(
instance.model_time,
-(particles[6].x - 0.5 *
(particles[4].x + particles[5].x)) / particles[6].vx, 3)
self.assertEquals(len(collisions.particles(0)), 1)
self.assertEquals(len(collisions.particles(1)), 1)
self.assertEquals(
len(instance.particles - collisions.particles(0) -
collisions.particles(1)), 2)
self.assertEquals(
abs(collisions.particles(0).x - collisions.particles(1).x) <
(collisions.particles(0).radius + collisions.particles(1).radius),
[True])
instance.stop()