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 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 evolve_system_with_massloss(particles, mass_sequence, time_sequence,
datahandler):
"""
Parameters
----------
particles: a two-body system
mass_sequence: sequence of masses
time_sequence: sequence of times
datahandler: HDF5HandlerAmuse context manager
"""
h = datahandler
intr = Hermite(nbody_to_si(particles.total_mass(), 1 | u.AU))
intr.particles.add_particles(particles)
h.append(particles[0].period0, "period0")
for mass, time in zip(mass_sequence, time_sequence):
intr.particles.move_to_center()
intr.evolve_model(time)
intr.particles[0].mass = mass
h.append(intr.particles.center_of_mass(), "CM_position")
h.append(intr.particles.center_of_mass_velocity(), "CM_velocity")
h.append(intr.particles.position, "position")
h.append(intr.particles.velocity, "velocity")
h.append(intr.particles.mass, "mass")
h.append(intr.particles.kinetic_energy(), "kinetic_energy")
h.append(intr.particles.potential_energy(), "potential_energy")
h.append(intr.get_total_energy(), "total_energy")
h.append(time, "time")
h.append(semimajoraxis_from_binary(intr.particles), "sma")
h.append(eccentricity_from_binary(intr.particles), "eccentricity")
intr.stop()
