def calcXa(x_ae, x_e):
    """
    Calculate the asteroid position vector.

    Parameters
    ----------
    x_ae : `~numpy.ndarray` (3)
        Topocenter to asteroid position vector in arbitrary units.
    x_e : `~numpy.ndarray` (3)
        Topocentric position vector in same units as x_ae.

    Returns
    -------
    x_a : `~numpy.ndarray` (3)
        Asteroid position vector in units of x_ae.
    """
    return x_ae + x_e