def test_kepler_2d_inverse():
t = 23
p = kepler.Kepler2DParameters(a=2, pb=3, eps1=0.2, eps2=0.1, t0=t - 1)
xyv, _ = kepler.kepler_2d(p, t)
m = kepler.mass(p.a, p.pb)
p2 = kepler.inverse_kepler_2d(xyv, m, t)
assert_allclose(p, p2, atol=1e-8)
def test_kepler_2d_derivs():
p = kepler.Kepler2DParameters(a=2, pb=3, eps1=0.2, eps2=0.1, t0=-1)
check_all_partials(
flatten_namedtuple(kepler.kepler_2d, kepler.Kepler2DParameters), list(p) + [4]
)
def test_kepler_2d_t0_pb():
p = kepler.Kepler2DParameters(a=2, pb=3, eps1=0.1, eps2=0.2, t0=1)
xyv, _ = kepler.kepler_2d(p, p.t0 + p.pb)
assert xyv[0] > 0
assert_allclose(xyv[1], 0, atol=1e-8)