def test_transform_unitless_vector():
vector = [0, 1, 0]
angle = 45 * u.deg
axis = 'z'
expected_vector = [np.sqrt(2) / 2, np.sqrt(2) / 2, 0]
result = util.transform(vector, angle, axis)
assert_allclose(result, expected_vector)
def test_transform_unitless_vector():
vector = [0, 1, 0]
angle = 45 * u.deg
axis = 'z'
expected_vector = [np.sqrt(2) / 2, np.sqrt(2) / 2, 0]
result = util.transform(vector, angle, axis)
assert_array_almost_equal(result, expected_vector)
def coe2rv(k, p, ecc, inc, raan, argp, nu):
"""Converts from classical orbital elements to vectors.
Parameters
----------
k : float
Standard gravitational parameter (km^3 / s^2).
p : float
Semi-latus rectum or parameter (km).
ecc : float
Eccentricity.
inc : float
Inclination (rad).
omega : float
Longitude of ascending node (rad).
argp : float
Argument of perigee (rad).
nu : float
True anomaly (rad).
"""
r_pqw, v_pqw = rv_pqw(k, p, ecc, nu)
r_ijk = transform(r_pqw, -argp, "z", u.rad)
r_ijk = transform(r_ijk, -inc, "x", u.rad)
r_ijk = transform(r_ijk, -raan, "z", u.rad)
v_ijk = transform(v_pqw, -argp, "z", u.rad)
v_ijk = transform(v_ijk, -inc, "x", u.rad)
v_ijk = transform(v_ijk, -raan, "z", u.rad)
return r_ijk, v_ijk
def coe2rv(k, p, ecc, inc, raan, argp, nu):
"""Converts from classical orbital elements to vectors.
Parameters
----------
k : float
Standard gravitational parameter (km^3 / s^2).
p : float
Semi-latus rectum or parameter (km).
ecc : float
Eccentricity.
inc : float
Inclination (rad).
omega : float
Longitude of ascending node (rad).
argp : float
Argument of perigee (rad).
nu : float
True anomaly (rad).
"""
r_pqw, v_pqw = rv_pqw(k, p, ecc, nu)
r_ijk = transform(r_pqw, -argp, 'z', u.rad)
r_ijk = transform(r_ijk, -inc, 'x', u.rad)
r_ijk = transform(r_ijk, -raan, 'z', u.rad)
v_ijk = transform(v_pqw, -argp, 'z', u.rad)
v_ijk = transform(v_ijk, -inc, 'x', u.rad)
v_ijk = transform(v_ijk, -raan, 'z', u.rad)
return r_ijk, v_ijk
def body_centered_to_icrs(r,
v,
source_body,
epoch=J2000,
rotate_meridian=False):
"""Converts position and velocity body-centered frame to ICRS.
Parameters
----------
r : ~astropy.units.Quantity
Position vector in a body-centered reference frame.
v : ~astropy.units.Quantity
Velocity vector in a body-centered reference frame.
source_body : Body
Source body.
epoch : ~astropy.time.Time, optional
Epoch, default to J2000.
rotate_meridian : bool, optional
Whether to apply the rotation of the meridian too, default to False.
Returns
-------
r, v : tuple (~astropy.units.Quantity)
Position and velocity vectors in ICRS.
"""
ra, dec, W = source_body.rot_elements_at_epoch(epoch)
if rotate_meridian:
r = transform(r, -W, 'z')
v = transform(v, -W, 'z')
r_trans1 = transform(r, -(90 * u.deg - dec), 'x')
r_trans2 = transform(r_trans1, -(90 * u.deg + ra), 'z')
v_trans1 = transform(v, -(90 * u.deg - dec), 'x')
v_trans2 = transform(v_trans1, -(90 * u.deg + ra), 'z')
icrs_frame_pos_coord, icrs_frame_vel_coord = get_body_barycentric_posvel(
source_body.name, time=epoch)
r_f = icrs_frame_pos_coord.xyz + r_trans2
v_f = icrs_frame_vel_coord.xyz + v_trans2
return r_f.to(r.unit), v_f.to(v.unit)
def icrs_to_body_centered(r,
v,
target_body,
epoch=J2000,
rotate_meridian=False):
"""Converts position and velocity in ICRS to body-centered frame.
Parameters
----------
r : ~astropy.units.Quantity
Position vector in ICRS.
v : ~astropy.units.Quantity
Velocity vector in ICRS.
target_body : Body
Target body.
epoch : ~astropy.time.Time, optional
Epoch, default to J2000.
rotate_meridian : bool, optional
Whether to apply the rotation of the meridian too, default to False.
Returns
-------
r, v : tuple (~astropy.units.Quantity)
Position and velocity vectors in a body-centered reference frame.
"""
ra, dec, W = target_body.rot_elements_at_epoch(epoch)
icrs_frame_pos_coord, icrs_frame_vel_coord = get_body_barycentric_posvel(
target_body.name, time=epoch)
r_trans1 = r - icrs_frame_pos_coord.xyz
r_trans2 = transform(r_trans1, (90 * u.deg + ra), 'z')
r_f = transform(r_trans2, (90 * u.deg - dec), 'x')
v_trans1 = v - icrs_frame_vel_coord.xyz
v_trans2 = transform(v_trans1, (90 * u.deg + ra), 'z')
v_f = transform(v_trans2, (90 * u.deg - dec), 'x')
if rotate_meridian:
r_f = transform(r_f, W, 'z')
v_f = transform(v_f, W, 'z')
return r_f.to(r.unit), v_f.to(v.unit)
