core.py 文件源码

def rho_as_angle(rho, eph):
    """Projected linear distance to angular distance.

    Parameters
    ----------
    rho : `~astropy.units.Quantity`
      Projected distance in units of length.

    eph : dictionary-like or `~sbpy.data.Ephem`
      Ephemerides; requires geocentric distance as `delta`.

    Returns
    -------
    rho_l : `~astropy.units.Quantity`

    """

    if rho.unit.is_equivalent(u.m):
        rho_a = np.arctan(rho / eph['delta'].to(u.m))
    else:
        assert rho.unit.is_equivalent(u.rad)
        rho_a = rho

    return rho_a