def test_center_of_mass():
t = np.linspace(0, 100, 1000)
m_planet = np.array([0.5, 0.1])
m_star = 1.45
orbit = KeplerianOrbit(
m_star=m_star,
r_star=1.0,
t0=np.array([0.5, 17.4]),
period=np.array([100.0, 37.3]),
ecc=np.array([0.1, 0.8]),
omega=np.array([0.5, 1.3]),
Omega=np.array([0.0, 1.0]),
incl=np.array([0.25 * np.pi, 0.3 * np.pi]),
m_planet=m_planet,
)
planet_coords = theano.function([], orbit.get_planet_position(t))()
star_coords = theano.function([], orbit.get_star_position(t))()
com = np.sum(
(m_planet[None, :] * np.array(planet_coords) +
m_star * np.array(star_coords)) / (m_star + m_planet)[None, :],
axis=0,
)
assert np.allclose(com, 0.0)
def test_flip_circular():
t = np.linspace(0, 100, 1000)
m_planet = 0.1
m_star = 1.3
orbit1 = KeplerianOrbit(
m_star=m_star,
r_star=1.1,
t0=0.5,
period=100.0,
Omega=1.0,
incl=0.25 * np.pi,
m_planet=m_planet,
)
orbit2 = orbit1._flip(0.7)
x1, y1, z1 = theano.function([], orbit1.get_star_position(t))()
x2, y2, z2 = theano.function([], orbit2.get_planet_position(t))()
assert np.allclose(x1, x2, atol=1e-5)
assert np.allclose(y1, y2, atol=1e-5)
assert np.allclose(z1, z2, atol=1e-5)
x1, y1, z1 = theano.function([], orbit1.get_planet_position(t))()
x2, y2, z2 = theano.function([], orbit2.get_star_position(t))()
assert np.allclose(x1, x2, atol=1e-5)
assert np.allclose(y1, y2, atol=1e-5)
assert np.allclose(z1, z2, atol=1e-5)
def test_velocity():
t_tensor = tt.dvector()
t = np.linspace(0, 100, 1000)
m_planet = 0.1
m_star = 1.3
orbit = KeplerianOrbit(
m_star=m_star,
r_star=1.0,
t0=0.5,
period=100.0,
ecc=0.1,
omega=0.5,
Omega=1.0,
incl=0.25 * np.pi,
m_planet=m_planet,
)
star_pos = orbit.get_star_position(t_tensor)
star_vel = theano.function([], orbit.get_star_velocity(t))()
star_vel_expect = np.empty_like(star_vel)
for i in range(3):
g = theano.grad(tt.sum(star_pos[i]), t_tensor)
star_vel_expect[i] = theano.function([t_tensor], g)(t)
assert np.allclose(star_vel, star_vel_expect)
planet_pos = orbit.get_planet_position(t_tensor)
planet_vel = theano.function([], orbit.get_planet_velocity(t))()
planet_vel_expect = np.empty_like(planet_vel)
for i in range(3):
g = theano.grad(tt.sum(planet_pos[i]), t_tensor)
planet_vel_expect[i] = theano.function([t_tensor], g)(t)
assert np.allclose(planet_vel, planet_vel_expect)
pos = orbit.get_relative_position(t_tensor)
vel = np.array(theano.function([], orbit.get_relative_velocity(t))())
vel_expect = np.empty_like(vel)
for i in range(3):
g = theano.grad(tt.sum(pos[i]), t_tensor)
vel_expect[i] = theano.function([t_tensor], g)(t)
assert np.allclose(vel, vel_expect)