def setup_codes(stars_below_cut, stars_above_cut, nbody_converter):
if len(stars_below_cut) is 0: # direct
print "There are zero stars below the cut-off, using direct solver!"
gravity = Hermite(nbody_converter, number_of_workers=4)
gravity.particles.add_particles(stars_above_cut)
channels = Channels()
channels.add_channel(gravity.particles.new_channel_to(stars_above_cut))
return gravity, channels # NB no bridge needed
if len(stars_above_cut) is 0: # tree
print "There are zero stars above the cut-off, using tree solver!"
gravity = BHTree(nbody_converter)
gravity.particles.add_particles(stars_below_cut)
channels = Channels()
channels.add_channel(gravity.particles.new_channel_to(stars_below_cut))
return gravity, channels # NB no bridge needed
gravity_low_mass = BHTree(nbody_converter)
gravity_low_mass.particles.add_particles(stars_below_cut)
gravity_high_mass = Hermite(nbody_converter, number_of_workers=4)
gravity_high_mass.particles.add_particles(stars_above_cut)
bridge = Bridge(timestep=0.01|units.Myr, use_threading=False)
bridge.add_system(gravity_low_mass, (gravity_high_mass,))
bridge.add_system(gravity_high_mass, (gravity_low_mass,))
channels = Channels()
channels.add_channel(gravity_low_mass.particles.new_channel_to(stars_below_cut))
channels.add_channel(gravity_high_mass.particles.new_channel_to(stars_above_cut))
return bridge, channels
def test13(self):
particles = plummer.new_plummer_model(31)
instance = Hermite(number_of_workers=1) #, debugger="xterm")
instance.initialize_code()
instance.parameters.epsilon_squared = 0.01 | nbody_system.length**2
instance.particles.add_particles(particles)
instance.evolve_model(0.1 | nbody_system.time)
instance.synchronize_model()
expected_positions = instance.particles.position
instance.stop()
positions_per_workers = []
for n in [2, 3, 4, 5]:
instance = Hermite(number_of_workers=n)
instance.initialize_code()
instance.parameters.epsilon_squared = 0.01 | nbody_system.length**2
instance.particles.add_particles(particles)
instance.evolve_model(0.1 | nbody_system.time)
instance.synchronize_model()
positions_per_workers.append(instance.particles.position)
instance.stop()
for index, n in enumerate([2, 3, 4, 5]):
self.assertAlmostEqual(expected_positions,
positions_per_workers[index], 15)
def test24(self):
hermite = Hermite(reuse_worker = True)
channel1 = hermite.legacy_interface.channel
hermite.stop()
hermite = Hermite(reuse_worker = True)
channel2 = hermite.legacy_interface.channel
hermite.stop()
self.assertEquals(id(channel1), id(channel2))
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.assertEquals(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 test6(self):
print "Test6: Testing Hermite parameters"
convert_nbody = nbody_system.nbody_to_si(1.0 | units.yr, 1.0 | units.AU)
instance = Hermite(convert_nbody)
value = instance.get_eps2()
self.assertEquals(0.0 | units.AU**2 , value)
self.assertAlmostEquals(0.0 | units.AU**2, instance.parameters.epsilon_squared, in_units=units.AU**2)
for x in [0.01, 0.1, 0.2]:
instance.parameters.epsilon_squared = x | units.AU**2
self.assertAlmostEquals(x | units.AU**2, instance.parameters.epsilon_squared, in_units=units.AU**2)
value = instance.get_dt_param()
self.assertEquals(0.03 , value)
self.assertAlmostEquals(0.03 , instance.parameters.dt_param)
for x in [0.001, 0.01, 0.1]:
instance.parameters.dt_param = x
self.assertAlmostEquals(x, instance.parameters.dt_param)
value = instance.get_dt_dia()
self.assertAlmostEquals(1.0 | units.yr, value)
self.assertAlmostEquals(1.0 | units.yr, instance.parameters.dt_dia, in_units=units.yr)
for x in [0.1, 10.0, 100.0]:
instance.parameters.dt_dia = x | units.yr
self.assertAlmostEquals(x | units.yr, instance.parameters.dt_dia, in_units=units.yr)
value = instance.get_begin_time()
self.assertEquals(0.0| units.yr, value)
self.assertAlmostEquals(0.0 | units.yr, instance.parameters.begin_time, in_units=units.yr)
for x in [1.0, 10.0, 100.0]:
instance.parameters.begin_time = x | units.yr
self.assertAlmostEquals(x | units.yr, instance.parameters.begin_time, in_units=units.yr)
instance.stop()
def test4(self):
convert_nbody = nbody_system.nbody_to_si(5.0 | units.kg, 10.0 | units.m)
instance = Hermite(convert_nbody)
instance.initialize_code()
particles = datamodel.Particles(2)
self.assertEquals(len(instance.particles), 0)
particles.mass = [15.0, 30.0] | units.kg
particles.radius = [10.0, 20.0] | units.m
particles.position = [[10.0, 20.0, 30.0], [20.0, 40.0, 60.0]] | units.m
particles.velocity = [[0.0, 0.0, 0.0], [0.0, 0.0, 0.0]] | units.m / units.s
instance.particles.add_particles(particles)
self.assertEquals(len(instance.particles), 2)
instance.particles.mass = [17.0, 33.0] | units.kg
self.assertEquals(instance.get_mass(0), 17.0| units.kg)
self.assertEquals(instance.get_mass(1), 33.0| units.kg)
instance.stop()
def test1(self):
convert_nbody = nbody_system.nbody_to_si(1.0 | units.MSun, 149.5e6 | units.km)
hermite = Hermite(convert_nbody)
hermite.initialize_code()
hermite.parameters.epsilon_squared = 0.0 | units.AU**2
hermite.parameters.end_time_accuracy_factor = 0.0
hermite.dt_dia = 5000
stars = self.new_system_of_sun_and_earth()
earth = stars[1]
hermite.particles.add_particles(stars)
hermite.evolve_model(365.0 | units.day)
hermite.particles.copy_values_of_all_attributes_to(stars)
position_at_start = earth.position.value_in(units.AU)[0]
position_after_full_rotation = earth.position.value_in(units.AU)[0]
self.assertAlmostRelativeEqual(position_at_start, position_after_full_rotation, 6)
hermite.evolve_model(365.0 + (365.0 / 2) | units.day)
hermite.particles.copy_values_of_all_attributes_to(stars)
position_after_half_a_rotation = earth.position.value_in(units.AU)[0]
self.assertAlmostRelativeEqual(-position_at_start, position_after_half_a_rotation, 3)
hermite.evolve_model(365.0 + (365.0 / 2) + (365.0 / 4) | units.day)
hermite.particles.copy_values_of_all_attributes_to(stars)
position_after_half_a_rotation = earth.position.value_in(units.AU)[1]
self.assertAlmostRelativeEqual(-position_at_start, position_after_half_a_rotation, 3)
hermite.cleanup_code()
hermite.stop()
def test21(self):
import pickle
convert_nbody = nbody_system.nbody_to_si(1.0 | units.MSun, 149.5e6 | units.km)
hermite = Hermite(convert_nbody)
encoded_interface = pickle.dumps(hermite,0)
decoded_interface = pickle.loads(encoded_interface)
def test5(self):
converter = nbody_system.nbody_to_si(units.MSun, units.parsec)
code = Hermite(converter)
stars = datamodel.Particles(keys=(1, 2))
stars.mass = converter.to_si(1 | nbody_system.mass)
stars.position = converter.to_si([[0, 0, 0], [1.2, 0, 0]]
| nbody_system.length)
stars.velocity = converter.to_si([[0, 0, 0], [0, 0.1, 0]]
| nbody_system.speed)
stars.radius = converter.to_si(0.5 | nbody_system.length)
encounter_code = encounters.HandleEncounter(
kepler_code=self.new_kepler_si(),
resolve_collision_code=self.new_smalln_si(),
interaction_over_code=None,
G=constants.G)
encounter_code.parameters.hard_binary_factor = 1
multiples_code = encounters.Multiples(
gravity_code=code,
handle_encounter_code=encounter_code,
G=constants.G)
end_time = converter.to_si(1.0 | nbody_system.time)
multiples_code.particles.add_particles(stars)
multiples_code.commit_particles()
multiples_code.evolve_model(end_time)
self.assertEquals(len(multiples_code.particles),
1) # 1 multiples with 2 singles
self.assertEquals(len(multiples_code.multiples), 1)
self.assertEquals(len(multiples_code.multiples[0].components), 2)
self.assertEquals(len(multiples_code.binaries), 1)
self.assertEquals(len(multiples_code.singles), 0)
def test12(self):
particles = datamodel.Particles(2)
particles.x = [0.0, 1.00] | nbody_system.length
particles.y = [0.0, 0.0] | nbody_system.length
particles.z = [0.0, 0.0] | nbody_system.length
particles.radius = 0.005 | nbody_system.length
particles.vx = [5.1, 0.0] | nbody_system.speed
particles.vy = [0.0, 0.0] | nbody_system.speed
particles.vz = [0.0, 0.0] | nbody_system.speed
particles.mass = [0.1, 0.1] | nbody_system.mass
instance = Hermite()
instance.initialize_code()
instance.parameters.stopping_conditions_out_of_box_size = .5 | nbody_system.length
self.assertEquals(
instance.parameters.stopping_conditions_out_of_box_size,
.5 | nbody_system.length)
instance.particles.add_particles(particles)
instance.stopping_conditions.out_of_box_detection.enable()
instance.evolve_model(0.1 | nbody_system.time)
self.assertTrue(
instance.stopping_conditions.out_of_box_detection.is_set())
self.assertAlmostEqual(
instance.stopping_conditions.out_of_box_detection.particles(0).x,
1.0 | nbody_system.length, 3)
instance.stop()
def test5(self):
convert_nbody = nbody_system.nbody_to_si(5.0 | units.kg,
10.0 | units.m)
instance = Hermite(convert_nbody)
instance.initialize_code()
particles = datamodel.Particles(2)
self.assertEquals(len(instance.particles), 0)
particles.mass = [15.0, 30.0] | units.kg
particles.radius = [10.0, 20.0] | units.m
particles.position = [[10.0, 20.0, 30.0], [20.0, 40.0, 60.0]] | units.m
particles.velocity = [[0.0, 0.0, 0.0], [0.0, 0.0, 0.0]
] | units.m / units.s
instance.particles.add_particles(particles)
self.assertEquals(len(instance.particles), 2)
instance.set_state(1, 16 | units.kg, 20.0 | units.m, 40.0 | units.m,
60.0 | units.m, 1.0 | units.ms, 1.0 | units.ms,
1.0 | units.ms, 20.0 | units.m)
curr_state = instance.get_state(1)
for expected, actual in zip([
16 | units.kg, 20.0 | units.m, 40.0 | units.m, 60.0 | units.m,
1.0 | units.ms, 1.0 | units.ms, 1.0 | units.ms, 20.0 | units.m
], curr_state):
self.assertAlmostRelativeEquals(expected, actual)
instance.stop()
self.assertEquals(curr_state[0], 16 | units.kg, 8)
def evolve_system(particles):
"""
Evolves the system using the Hermite integrator.
Parameters
----------
particles: amuse.datamodel.particles.Particles instance
"""
times = numpy.linspace(0.0001, args.time, args.steps) | u.yr
intr = Hermite(nbody_to_si(particles.total_mass(), 1 | u.AU))
intr.particles.add_particles(particles)
energy_begin = intr.get_total_energy()
if args.dt is not None:
intr.set_dt_param(args.dt)
for t in times:
intr.evolve_model(t)
energy_error = (intr.get_total_energy() - energy_begin) / energy_begin
print(intr.get_time_step().in_(u.day), intr.get_time().in_(u.yr))
print(energy_error)
print("energy error:{}".format(energy_error))
intr.stop()
def parent_worker():
code = Hermite(conv)
code.parameters.epsilon_squared = 0. | units.AU**2
code.parameters.end_time_accuracy_factor = 0.
code.parameters.dt_param = 0.001
print(code.parameters.dt_dia.in_(units.yr))
return code
def test3(self):
code = Hermite()
particles_in_binary = self.new_binary(0.1 | nbody_system.mass,
0.1 | nbody_system.mass,
0.01 | nbody_system.length,
keyoffset=1)
particles_in_binary.radius = 0.001 | nbody_system.length
binary = datamodel.Particle(key=3)
binary.child1 = particles_in_binary[0]
binary.child2 = particles_in_binary[1]
binary.radius = 0.5 | nbody_system.length
binary.mass = 0.2 | nbody_system.mass
encounter_code = encounters.HandleEncounter(
kepler_code=self.new_kepler(),
resolve_collision_code=self.new_smalln(),
interaction_over_code=None)
multiples_code = encounters.Multiples(
gravity_code=code, handle_encounter_code=encounter_code)
multiples_code.singles_in_binaries.add_particles(particles_in_binary)
multiples_code.binaries.add_particle(binary)
self.assertEquals(len(multiples_code.singles_in_binaries), 2)
self.assertEquals(id(multiples_code.binaries[0].child1.particles_set),
id(multiples_code.singles_in_binaries))
multiples_code.commit_particles()
self.assertEquals(len(multiples_code.multiples), 1)
self.assertEquals(len(multiples_code.components_of_multiples), 2)
def evolve_model(self):
convert_nbody = nbody_system.nbody_to_si(1.0 | units.MSun,
149.5e6 | units.km)
hermite = Hermite(convert_nbody)
hermite.initialize_code()
hermite.parameters.epsilon_squared = 0.0 | units.AU**2
stars = self.new_system_of_sun_and_earth()
earth = stars[1]
sun = stars[0]
Earth = blender.Primitives.sphere(10, 10, 0.1) # Make the earth avatar
Sun = blender.Primitives.sphere(32, 32, 1) # Make the sun avatar
hermite.particles.add_particles(stars)
for i in range(1 * 365):
hermite.evolve_model(i | units.day)
hermite.particles.copy_values_of_all_attributes_to(stars)
# update avatar positions:
Earth.loc = (1 * earth.position.value_in(units.AU)[0],
1 * earth.position.value_in(units.AU)[1],
earth.position.value_in(units.AU)[2])
Sun.loc = (1 * sun.position.value_in(units.AU)[0],
1 * sun.position.value_in(units.AU)[1],
sun.position.value_in(units.AU)[2])
blender.Redraw()
hermite.print_refs()
hermite.stop()
def test2(self):
code = Hermite()
stars = datamodel.Particles(keys=(1, 2, 3, 4))
stars.mass = 1 | nbody_system.mass
stars.position = [
[0, 0, 0],
[0.5, 0, 0],
[2, 0, 0],
[-10, 0, 0],
] | nbody_system.length
stars.velocity = [
[0, 0, 0],
[0, 0.1, 0],
[0, -0.1, 0],
[0, 0.2, 0],
] | nbody_system.speed
stars.radius = 0.5 | nbody_system.length
encounter_code = encounters.HandleEncounter(
kepler_code=self.new_kepler(),
resolve_collision_code=self.new_smalln(),
interaction_over_code=None)
multiples_code = encounters.Multiples(
gravity_code=code, handle_encounter_code=encounter_code)
multiples_code.particles.add_particles(stars)
multiples_code.commit_particles()
multiples_code.evolve_model(3 | nbody_system.time)
self.assertEquals(len(multiples_code.multiples), 1)
self.assertEquals(len(multiples_code.multiples[0].components), 2)
self.assertEquals(len(multiples_code.particles), 3)
self.assertEquals(len(multiples_code.binaries), 1)
self.assertEquals(len(multiples_code.singles), 2)
def test3(self):
convert_nbody = nbody_system.nbody_to_si(1.0 | units.MSun,
149.5e6 | units.km)
instance = Hermite(convert_nbody)
instance.initialize_code()
instance.parameters.epsilon_squared = 0.00001 | units.AU**2
instance.dt_dia = 5000
stars = datamodel.Stars(2)
star1 = stars[0]
star2 = stars[1]
star1.mass = units.MSun(1.0)
star1.position = units.AU(numpy.array((-1.0, 0.0, 0.0)))
star1.velocity = units.AUd(numpy.array((0.0, 0.0, 0.0)))
star1.radius = units.RSun(1.0)
star2.mass = units.MSun(1.0)
star2.position = units.AU(numpy.array((1.0, 0.0, 0.0)))
star2.velocity = units.AUd(numpy.array((0.0, 0.0, 0.0)))
star2.radius = units.RSun(100.0)
instance.particles.add_particles(stars)
for x in range(1, 2000, 10):
instance.evolve_model(x | units.day)
instance.particles.copy_values_of_all_attributes_to(stars)
stars.savepoint()
instance.stop()
def simulate_system_until(particles, end_time):
convert_nbody = nbody_system.nbody_to_si(1.0 | units.MSun,
149.5e6 | units.km)
instance = Hermite(convert_nbody)
instance.parameters.epsilon_squared = 0.0 | units.AU**2
instance.particles.add_particles(particles)
t0 = 0 | units.day
dt = 10 | units.day
t = t0
earth = instance.particles[1]
x_values = quantities.AdaptingVectorQuantity()
y_values = quantities.AdaptingVectorQuantity()
while t < end_time:
instance.evolve_model(t)
x_values.append(earth.x)
y_values.append(earth.y)
t += dt
instance.stop()
return x_values, y_values
def test22(self):
hermite = Hermite()
hermite.parameters.epsilon_squared = 0.0 | nbody_system.length**2
particles = datamodel.Particles(2)
particles.position = ([0, 0, 0], [1, 0, 0]) | nbody_system.length
particles.velocity = ([-2, 0, 0], [2, 0, 0]) | nbody_system.speed
particles.radius = 0 | nbody_system.length
particles.mass = 0.1 | nbody_system.mass
hermite.particles.add_particles(particles)
hermite.stopping_conditions.out_of_box_detection.enable()
hermite.parameters.stopping_conditions_out_of_box_size = 2 | nbody_system.length
hermite.parameters.stopping_conditions_out_of_box_use_center_of_mass = False
hermite.evolve_model(1 | nbody_system.time)
print hermite.particles.x
print hermite.particles.key, particles[1].key
print hermite.stopping_conditions.out_of_box_detection.particles(0)
self.assertTrue(
hermite.stopping_conditions.out_of_box_detection.is_set())
self.assertEquals(
len(hermite.stopping_conditions.out_of_box_detection.particles(0)),
1)
self.assertEquals(
hermite.stopping_conditions.out_of_box_detection.particles(0)
[0].key, particles[1].key)
hermite.stop()
def simulate_small_cluster(number_of_stars=1000,
end_time=40 | nbody_system.time,
number_of_workers=1):
particles = new_plummer_model(number_of_stars)
particles.scale_to_standard()
gravity = Hermite(number_of_workers=number_of_workers)
gravity.parameters.epsilon_squared = 0.15 | nbody_system.length**2
gravity.particles.add_particles(particles)
from_gravity_to_model = gravity.particles.new_channel_to(particles)
time = 0.0 * end_time
total_energy_at_t0 = gravity.kinetic_energy + gravity.potential_energy
positions_at_different_times = []
positions_at_different_times.append(particles.position)
times = []
times.append(time)
print("evolving the model until t = " + str(end_time))
while time < end_time:
time += end_time / 3.0
gravity.evolve_model(time)
from_gravity_to_model.copy()
positions_at_different_times.append(particles.position)
times.append(time)
print_log(time, gravity, particles, total_energy_at_t0)
gravity.stop()
return times, positions_at_different_times
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.assertEquals(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.assertEquals(instance.particles[0].radius,
0.0 | nbody_system.length)
self.assertEquals(instance.particles[1].radius,
0.0 | nbody_system.length)
self.assertEquals(instance.particles[2].radius,
4.0 | nbody_system.length)
instance.stop()
def test11(self):
code = Hermite()
particles_in_binary = self.new_binary(1 | nbody_system.mass,
1 | nbody_system.mass,
0.001 | nbody_system.length,
keyoffset=1)
particles_in_binary.radius = 0.01 | nbody_system.length
encounter_code = encounters.HandleEncounter(
kepler_code=self.new_kepler(),
resolve_collision_code=self.new_smalln(),
)
others = datamodel.Particles(keys=[4, 5, 6])
for i in range(3):
others[i].position = [i, 0, 0] | nbody_system.length
others[i].velocity = [0, 0, 0] | nbody_system.speed
others[i].mass = 0.2 | nbody_system.mass
others[i].radius = 0.05 | nbody_system.length
multiples_code = encounters.Multiples(
gravity_code=code, handle_encounter_code=encounter_code)
multiples_code.singles.add_particles(particles_in_binary)
multiples_code.singles.add_particles(others)
stopping_condition = multiples_code.stopping_conditions.binaries_change_detection
stopping_condition.enable()
multiples_code.commit_particles()
multiples_code.evolve_model(1 | nbody_system.time)
self.assertEquals(len(multiples_code.multiples), 1)
self.assertEquals(len(multiples_code.binaries), 1)
self.assertEquals(len(multiples_code.components_of_multiples), 2)
self.assertEquals(len(multiples_code.singles), 3)
self.assertEquals(len(multiples_code.particles), 4)
self.assertEquals(len(code.particles), 4)
self.assertTrue(stopping_condition.is_set())
multiples_code.particles[-1].velocity = [0, 0, 0] | nbody_system.speed
multiples_code.update_model()
print multiples_code.particles.key
self.assertEquals(len(stopping_condition.particles(0)), 1)
self.assertEquals(len(stopping_condition.particles(1)), 0)
self.assertEquals(len(stopping_condition.particles(2)), 0)
self.assertAlmostRelativeEquals(multiples_code.multiples[0].mass,
2.0 | nbody_system.mass)
self.assertAlmostRelativeEquals(multiples_code.particles.mass.sum(),
2.6 | nbody_system.mass)
print multiples_code.particles.velocity
multiples_code.evolve_model(2 | nbody_system.time)
self.assertTrue(stopping_condition.is_set())
self.assertEquals(len(stopping_condition.particles(0)), 0)
self.assertEquals(len(stopping_condition.particles(1)), 0)
self.assertEquals(len(stopping_condition.particles(2)), 1)
self.assertAlmostRelativeEquals(multiples_code.multiples[0].mass,
2.0 | nbody_system.mass)
self.assertAlmostRelativeEquals(multiples_code.particles.mass.sum(),
2.6 | nbody_system.mass)
def set_up_gravitational_dynamics_code(stars):
convert_nbody = nbody_to_si(11.0 | units.MSun, 10.0 | units.AU)
gravitational_dynamics = Hermite(convert_nbody)
gravitational_dynamics.parameters.epsilon_squared = 0.0 | units.AU**2
view_on_the_primary = gravitational_dynamics.particles.add_particle(
stars[0])
gravitational_dynamics.particles.add_particle(stars[1])
return gravitational_dynamics, view_on_the_primary
def test4(self):
code = Hermite()
stars = datamodel.Particles(keys=(1, 2, 3, 4))
stars.mass = 1 | nbody_system.mass
stars.position = [
[0, 0, 0],
[0.5, 0, 0],
[2, 0, 0],
[-10, 0, 0],
] | nbody_system.length
stars.velocity = [
[0, 0, 0],
[0, 0.1, 0],
[0, -0.1, 0],
[0, 0.2, 0],
] | nbody_system.speed
stars.radius = 0.5 | nbody_system.length
encounter_code = encounters.HandleEncounter(
kepler_code=self.new_kepler(),
resolve_collision_code=self.new_smalln(),
interaction_over_code=None)
multiples_code = encounters.Multiples(
gravity_code=code, handle_encounter_code=encounter_code)
multiples_code.particles.add_particles(stars)
multiples_code.commit_particles()
stopping_condition = multiples_code.stopping_conditions.multiples_change_detection
stopping_condition.enable()
multiples_code.evolve_model(3 | nbody_system.time)
self.assertTrue(stopping_condition.is_set())
self.assertAlmostRelativeEquals(multiples_code.model_time,
0.0075 | nbody_system.time, 4)
self.assertEquals(len(stopping_condition.particles(0)), 1)
self.assertEquals(len(stopping_condition.particles(1)), 0)
self.assertEquals(len(multiples_code.multiples), 1)
self.assertEquals(len(multiples_code.multiples[0].components), 2)
self.assertEquals(len(multiples_code.particles),
3) # 1 multiples with 2 singles, plus 2 singles free
self.assertEquals(len(multiples_code.binaries), 1)
self.assertEquals(len(multiples_code.singles), 2)
multiples_code.evolve_model(3 | nbody_system.time)
self.assertTrue(stopping_condition.is_set())
self.assertAlmostRelativeEquals(multiples_code.model_time,
1.19126 | nbody_system.time, 4)
self.assertEquals(len(stopping_condition.particles(0)),
1) # 1 new multiple
self.assertEquals(len(stopping_condition.particles(1)),
1) # 1 dissolved multiple
self.assertEquals(len(multiples_code.multiples[0].components), 2)
self.assertEquals(len(multiples_code.particles),
3) # 1 multiples with 2 singles, plus 2 singles free
self.assertEquals(len(multiples_code.binaries), 1)
self.assertEquals(len(multiples_code.singles), 2)
def test8(self):
print "Testing Hermite collision_detection"
particles = datamodel.Particles(7)
particles.mass = 0.001 | nbody_system.mass
particles.radius = 0.01 | 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 = Hermite()
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.assertTrue(instance.model_time < 0.5 | nbody_system.time)
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 = datamodel.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.assertTrue(instance.model_time < 1.0 | nbody_system.time)
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()
def test6(self):
converter = nbody_system.nbody_to_si(units.MSun, units.parsec)
code = Hermite(converter)
stars = datamodel.Particles(keys=(1, 2, 3, 4))
stars.mass = converter.to_si(1 | nbody_system.mass)
stars.position = converter.to_si(
[[0, 0, 0], [1.2, 0, 0], [100, 0, 0], [100, 1.2, 0]]
| nbody_system.length)
stars.velocity = converter.to_si([
[0, 0, 0],
[0, 0.1, 0],
[0, 0, 0],
[0, 0, 0.1],
] | nbody_system.speed)
stars.radius = converter.to_si(0.5 | nbody_system.length)
encounter_code = encounters.HandleEncounter(
kepler_code=self.new_kepler_si(),
resolve_collision_code=self.new_smalln_si(),
interaction_over_code=None,
G=constants.G)
encounter_code.small_scale_factor = 1.0
multiples_code = encounters.Multiples(
gravity_code=code,
handle_encounter_code=encounter_code,
G=constants.G)
multiples_code.must_handle_one_encounter_per_stopping_condition = False
multiples_code.particles.add_particles(stars)
multiples_code.commit_particles()
stopping_condition = multiples_code.stopping_conditions.multiples_change_detection
stopping_condition.enable()
end_time = converter.to_si(3.0 | nbody_system.time)
print end_time.as_quantity_in(units.Myr)
multiples_code.evolve_model(end_time)
self.assertTrue(stopping_condition.is_set())
print multiples_code.model_time.as_quantity_in(units.Myr)
self.assertAlmostRelativeEquals(multiples_code.model_time,
7.99844 | units.Myr, 4)
self.assertEquals(len(stopping_condition.particles(0)), 2)
self.assertEquals(len(stopping_condition.particles(1)), 0)
self.assertEquals(len(multiples_code.particles),
2) # 1 multiples with 2 singles
self.assertEquals(len(multiples_code.multiples), 2)
self.assertEquals(len(multiples_code.binaries), 2)
self.assertEquals(len(multiples_code.multiples[0].components), 2)
self.assertEquals(len(multiples_code.multiples[1].components), 2)
self.assertEquals(len(multiples_code.singles), 0)
self.assertEquals(len(multiples_code.all_singles), 4)
def test_hermite(self):
convert_nbody = nbody_system.nbody_to_si(1.0 | units.kg, 1.0 | units.km)
hermite = Hermite(convert_nbody)
hermite.parameters.epsilon_squared = 10 | units.km**2
docstring = hermite.parameters.__doc__
self.assertTrue("smoothing parameter for gravity calculations (default value:0.0 m**2)" in docstring)
parameter_str_method_output = str(hermite.parameters)
self.assertTrue("epsilon_squared: 10000000.0 m**2" in parameter_str_method_output)
def test16(self):
particles = new_plummer_model(200)
particles.scale_to_standard()
instance = Hermite()
instance.initialize_code()
instance.parameters.epsilon_squared = 0.00000 | nbody_system.length**2
instance.particles.add_particles(particles)
x = numpy.arange(-1, 1, 0.1) | nbody_system.length
zero = numpy.zeros(len(x)) | nbody_system.length
potential0 = instance.get_potential_at_point(zero, x, zero, zero)
instance.stop()
for n in (2, 3, 4):
instance = Hermite(number_of_workers=n)
instance.initialize_code()
instance.parameters.epsilon_squared = 0.00000 | nbody_system.length**2
instance.particles.add_particles(particles)
potential = instance.get_potential_at_point(zero, x, zero, zero)
self.assertAlmostRelativeEquals(potential0, potential, 8)
instance.stop()
def test14(self):
code = Hermite()
encounter_code = encounters.HandleEncounter(
kepler_code=self.new_kepler(),
resolve_collision_code=self.new_smalln(),
)
center_of_mass_particles = datamodel.Particles(5)
center_of_mass_particles.position = (numpy.asarray(range(5))).reshape(
5, 1) * ([1.0, 0.0, 0.0] | nbody_system.length)
center_of_mass_particles.velocity = [0.0, 0.0, 0.0
] | nbody_system.speed
center_of_mass_particles.radius = 0.05 | nbody_system.length
binaries, singles_in_binaries = self.create_binaries(
center_of_mass_particles, 1 | nbody_system.mass,
0.1 | nbody_system.mass, 0.00000001 | nbody_system.length)
multiples_code = encounters.Multiples(
gravity_code=code, handle_encounter_code=encounter_code)
multiples_code.singles_in_binaries.add_particles(singles_in_binaries)
multiples_code.binaries.add_particles(binaries)
multiples_code.commit_particles()
#stopping_condition = multiples_code.stopping_conditions.encounter_detection
#stopping_condition.enable()
stopping_condition = multiples_code.stopping_conditions.binaries_change_detection
stopping_condition.enable()
for x in multiples_code.binaries:
print x.key, x.child1.key, x.child2.key
multiples_code.evolve_model(2 | nbody_system.time)
self.assertTrue(stopping_condition.is_set())
for x in multiples_code.binaries:
print x.key, x.child1.key, x.child2.key
for x in stopping_condition.particles(0):
print "NEW:", x.key, x.child1.key, x.child2.key
for x in stopping_condition.particles(1):
print "REMOVED:", x.key, x.child1.key, x.child2.key
for x in stopping_condition.particles(2):
print "UPDATED:", x.key, x.child1.key, x.child2.key
for x in multiples_code.singles:
print x.key, x.mass
self.assertEquals(
len(multiples_code.singles_in_binaries) +
len(multiples_code.singles), 2 * len(center_of_mass_particles))
self.assertEquals(
len(multiples_code.binaries) -
len(stopping_condition.particles(0)) +
len(stopping_condition.particles(1)),
len(center_of_mass_particles))
def test17(self):
particles = new_plummer_model(50)
particles.scale_to_standard()
instance = Hermite()
instance.parameters.epsilon_squared = 0.22000 | nbody_system.length**2
instance.particles.add_particles(particles)
self.assertEquals(len(instance.particles), 50)
instance.reset()
self.assertAlmostRelativeEquals(instance.parameters.epsilon_squared,
0.22000 | nbody_system.length**2)
self.assertEquals(len(instance.particles), 0)
instance.particles.add_particles(particles)
self.assertEquals(len(instance.particles), 50)
