def test13(self):
"""
tests generating cartesian coordinates from orbital elements
"""
numpy.random.seed(17014)
N = 5
mass1 = 1.0 | units.MSun
mass2 = numpy.ones(N) * 0.01 | units.MEarth
sem = 2. | units.AU
ecc = 0.15
inc = 11. | units.deg
lon = 30. | units.deg
arg = 0.3 | units.deg
ta = (360. * random.random() - 180.) | units.deg
rel_pos, rel_vel = rel_posvel_arrays_from_orbital_elements(
mass1, mass2, sem, ecc, ta, inc, lon, arg, G=constants.G)
mass_12 = mass1 + mass2
sem_ext, ecc_ext, ta_ext, inc_ext, lon_ext, arg_ext = \
orbital_elements(
rel_pos, rel_vel, mass_12, G=constants.G)
self.assertAlmostEqual(sem, sem_ext)
self.assertAlmostEqual(ecc, ecc_ext)
self.assertAlmostEqual(inc, inc_ext)
self.assertAlmostEqual(lon, lon_ext)
self.assertAlmostEqual(arg, arg_ext)
self.assertAlmostEqual(ta, ta_ext)
def test14(self):
"""
tests generating cartesian coordinates from orbital elements
"""
numpy.random.seed(17018)
N = 5
mass1 = numpy.ones(N) * 1.0 | units.MSun
mass2 = random.random(N) | units.MEarth
sem = numpy.array([2., 1.0, 1.1, 1.2, 4.0]) | units.AU
ecc = numpy.array([0.15, 0.01, 0.5, 0.9, 0.99])
inc = numpy.array([11., 0.1, 20, 90, 180.]) | units.deg
lon = numpy.array([31., 32., 33., 45., 30.]) | units.deg
arg = numpy.array([0.3, 11., 15., 30., 95.]) | units.deg
ta = (360. * random.random(N) - 180.) | units.deg
rel_pos, rel_vel = rel_posvel_arrays_from_orbital_elements(
mass1, mass2, sem, ecc, ta, inc, lon, arg, G=constants.G)
mass_12 = mass1 + mass2
sem_ext, ecc_ext, ta_ext, inc_ext, lon_ext, arg_ext = \
orbital_elements(
rel_pos, rel_vel, mass_12, G=constants.G)
self.assertAlmostEqual(sem.value_in(units.AU),
sem_ext.value_in(units.AU))
self.assertAlmostEqual(ecc, ecc_ext)
self.assertAlmostEqual(inc, inc_ext)
self.assertAlmostEqual(lon, lon_ext)
self.assertAlmostEqual(arg, arg_ext)
self.assertAlmostEqual(ta, ta_ext)
def gen_trappist_system(seed):
random.seed(seed)
bodies = Particles()
# Put the star at the center of the system
star = Particle()
star.mass = star_mass
star.radius = star_radius
star.position = [0, 0, 0] | units.AU
star.velocity = [0, 0, 0] | units.kms
bodies.add_particle(star)
# Randomly generate the LANs
longitude_of_ascending_nodes = gen_random_data(len(masses), -np.pi / 20,
np.pi / 20, units.rad)
# Get position and velocities by calculating them from orbital parameters.
positions, velocities = rel_posvel_arrays_from_orbital_elements(star_mass, masses, semimajor_axes, eccentricities, mean_anomalies, inclinations.number, \
longitude_of_ascending_nodes, argument_of_periapses.number, G=constants.G)
for i in range(len(masses)):
planet = Particle()
planet.mass = masses[i]
planet.radius = radii[i]
planet.position = positions[i]
planet.velocity = velocities[i]
bodies.add_particle(planet)
return bodies