def _kepler(k, r0, v0, tof, *, numiter):
# Compute Lagrange coefficients
f, g, fdot, gdot = kepler_fast(k, r0, v0, tof, numiter)
assert np.abs(f * gdot - fdot * g - 1) < 1e-5 # Fixed tolerance
# Return position and velocity vectors
r = f * r0 + g * v0
v = fdot * r0 + gdot * v0
return r, v
def _kepler(k, r0, v0, tof, *, numiter):
# Compute Lagrange coefficients
f, g, fdot, gdot = kepler_fast(k, r0, v0, tof, numiter)
assert np.abs(f * gdot - fdot * g - 1) < 1e-5 # Fixed tolerance
# Return position and velocity vectors
r = f * r0 + g * v0
v = fdot * r0 + gdot * v0
return r, v
def _kepler(orbit, tof, *, numiter):
"""Propagates Keplerian orbit.
Parameters
----------
orbit : ~poliastro.twobody.orbit.Orbit
the Orbit object to propagate.
tof : float
Time of flight (s).
numiter : int, optional
Maximum number of iterations, default to 35.
Raises
------
RuntimeError
If the algorithm didn't converge.
Note
-----
This algorithm is based on Vallado implementation, and does basic Newton
iteration on the Kepler equation written using universal variables. Battin
claims his algorithm uses the same amount of memory but is between 40 %
and 85 % faster.
"""
# Compute Lagrange coefficients
k = orbit.attractor.k.to(u.km**3 / u.s**2).value
r0 = orbit.r.to(u.km).value
v0 = orbit.v.to(u.km / u.s).value
f, g, fdot, gdot = kepler_fast(k, r0, v0, tof, numiter)
assert np.abs(f * gdot - fdot * g - 1) < 1e-5 # Fixed tolerance
# Return position and velocity vectors
r = f * r0 + g * v0
v = fdot * r0 + gdot * v0
return r, v
def _kepler(orbit, tof, *, numiter):
"""Propagates Keplerian orbit.
Parameters
----------
orbit : ~poliastro.twobody.orbit.Orbit
the Orbit object to propagate.
tof : float
Time of flight (s).
numiter : int, optional
Maximum number of iterations, default to 35.
Raises
------
RuntimeError
If the algorithm didn't converge.
Note
-----
This algorithm is based on Vallado implementation, and does basic Newton
iteration on the Kepler equation written using universal variables. Battin
claims his algorithm uses the same amount of memory but is between 40 %
and 85 % faster.
"""
# Compute Lagrange coefficients
k = orbit.attractor.k.to(u.km ** 3 / u.s ** 2).value
r0 = orbit.r.to(u.km).value
v0 = orbit.v.to(u.km / u.s).value
f, g, fdot, gdot = kepler_fast(k, r0, v0, tof, numiter)
assert np.abs(f * gdot - fdot * g - 1) < 1e-5 # Fixed tolerance
# Return position and velocity vectors
r = f * r0 + g * v0
v = fdot * r0 + gdot * v0
return r, v