def run_smallN(
particles,
end_time = 1000 | nbody_system.time,
delta_t = 10 | nbody_system.time,
accuracy_parameter = 0.1
):
gravity = SmallN(redirection = "none") # , debugger="gdb")
gravity.initialize_code()
gravity.parameters.set_defaults()
gravity.parameters.timestep_parameter = accuracy_parameter
gravity.parameters.cm_index = 2001
gravity.commit_parameters()
time = 0 | nbody_system.time
print "\nadding particles to smallN"
sys.stdout.flush()
gravity.set_time(time);
gravity.particles.add_particles(particles)
print "committing particles to smallN"
gravity.commit_particles()
print "smallN: number_of_stars =", len(particles)
print "smallN: evolving to time =", end_time.number,
print "in steps of", delta_t.number
sys.stdout.flush()
E0 = print_log('smallN', gravity)
# Channel to copy values from the code to the set in memory.
channel = gravity.particles.new_channel_to(particles)
while time < end_time:
time += delta_t
print 'evolving smallN to time', time.number
sys.stdout.flush()
gravity.evolve_model(time)
print_log('smallN', gravity, E0)
over = gravity.is_over()
if over.number:
print 'interaction is over\n'; sys.stdout.flush()
# Create a tree in the module representing the binary structure.
gravity.update_particle_tree()
# Return the tree structure to AMUSE. Children are
# identified by get_children_of_particle in interface.??,
# and the information is returned in the copy operation.
gravity.update_particle_set()
gravity.particles.synchronize_to(particles)
channel.copy()
channel.copy_attribute("index_in_code", "id")
gravity.stop()
# Basic diagnostics: BinaryTreesOnAParticleSet creates
# binary tree structure for all particles in the set; then
# we loop over roots (top-level nodes) and print data on
# all binaries below each.
print "smallN binaries:"; sys.stdout.flush()
x = trees.BinaryTreesOnAParticleSet(particles, "child1", "child2")
roots = list(x.iter_roots())
for r in roots:
for level, particle in r.iter_levels():
print ' '*level, int(particle.id.number),
if not particle.child1 is None:
M,a,e,r,E = get_cm_binary_elements(particle)
print " mass = %.5e" % (M.number)
m1 = particle.child1.mass
m2 = particle.child2.mass
print_elements(' ', a, e, r, E*m1*m2/M)
else:
print ''
sys.stdout.flush()
return E0
sys.stdout.flush()
gravity.stop()
raise Exception("Did not finish the small-N simulation "
+"before end time {0}".format(end_time))
def run_smallN(particles,
end_time=1000 | nbody_system.time,
delta_t=10 | nbody_system.time,
accuracy_parameter=0.1):
gravity = SmallN(redirection="none") # , debugger="gdb")
gravity.initialize_code()
gravity.parameters.set_defaults()
gravity.parameters.timestep_parameter = accuracy_parameter
gravity.parameters.cm_index = 2001
gravity.commit_parameters()
time = 0 | nbody_system.time
print("\nadding particles to smallN")
sys.stdout.flush()
gravity.set_time(time)
gravity.particles.add_particles(particles)
print("committing particles to smallN")
gravity.commit_particles()
print("smallN: number_of_stars =", len(particles))
print("smallN: evolving to time =", end_time.number, end=' ')
print("in steps of", delta_t.number)
sys.stdout.flush()
E0 = print_log('smallN', gravity)
# Channel to copy values from the code to the set in memory.
channel = gravity.particles.new_channel_to(particles)
while time < end_time:
time += delta_t
print('evolving smallN to time', time.number)
sys.stdout.flush()
gravity.evolve_model(time)
print_log('smallN', gravity, E0)
over = gravity.is_over()
if over.number:
print('interaction is over\n')
sys.stdout.flush()
# Create a tree in the module representing the binary structure.
gravity.update_particle_tree()
# Return the tree structure to AMUSE. Children are
# identified by get_children_of_particle in interface.??,
# and the information is returned in the copy operation.
gravity.update_particle_set()
gravity.particles.synchronize_to(particles)
channel.copy()
channel.copy_attribute("index_in_code", "id")
gravity.stop()
# Basic diagnostics: BinaryTreesOnAParticleSet creates
# binary tree structure for all particles in the set; then
# we loop over roots (top-level nodes) and print data on
# all binaries below each.
print("smallN binaries:")
sys.stdout.flush()
x = trees.BinaryTreesOnAParticleSet(particles, "child1", "child2")
roots = list(x.iter_roots())
for r in roots:
for level, particle in r.iter_levels():
print(' ' * level, int(particle.id.number), end=' ')
if not particle.child1 is None:
M, a, e, r, E = get_cm_binary_elements(particle)
print(" mass = %.5e" % (M.number))
m1 = particle.child1.mass
m2 = particle.child2.mass
print_elements(' ', a, e, r, E * m1 * m2 / M)
else:
print('')
sys.stdout.flush()
return E0
sys.stdout.flush()
gravity.stop()
raise Exception("Did not finish the small-N simulation " +
"before end time {0}".format(end_time))
