def D_to_nu(D):
    """True anomaly from parabolic eccentric anomaly.

    Parameters
    ----------
    D : ~astropy.units.Quantity
        Eccentric anomaly.

    Returns
    -------
    nu : ~astropy.units.Quantity
        True 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 (D_to_nu_fast(D.to_value(u.rad)) * u.rad).to(D.unit)