def nu_to_D(nu):
"""Parabolic eccentric anomaly from true anomaly.
Parameters
----------
nu : ~astropy.units.Quantity
True anomaly.
Returns
-------
D : ~astropy.units.Quantity
Hyperbolic eccentric anomaly.
Notes
-----
Taken from Farnocchia, Davide, Davide Bracali Cioci, and Andrea Milani.
"Robust resolution of Kepler’s equation in all eccentricity regimes."
Celestial Mechanics and Dynamical Astronomy 116, no. 1 (2013): 21-34.
"""
return (nu_to_D_fast(nu.to(u.rad).value) * u.rad).to(nu.unit)
def nu_to_D(nu):
"""Parabolic eccentric anomaly from true anomaly.
Parameters
----------
nu : ~astropy.units.Quantity
True anomaly.
Returns
-------
D : ~astropy.units.Quantity
Hyperbolic eccentric anomaly.
Notes
-----
Taken from Farnocchia, Davide, Davide Bracali Cioci, and Andrea Milani.
"Robust resolution of Kepler’s equation in all eccentricity regimes."
Celestial Mechanics and Dynamical Astronomy 116, no. 1 (2013): 21-34.
"""
return (nu_to_D_fast(nu.to(u.rad).value) * u.rad).to(nu.unit)