def antipode(lon, lat):
    """
    Calculates the antipode (opposite point on the globe) of the given point or
    points. Input and output is expected to be in radians.

    Parameters
    ----------
    lon : number or sequence of numbers
        Longitude in radians
    lat : number or sequence of numbers
        Latitude in radians

    Returns
    -------
    lon, lat : arrays
        Sequences (regardless of whether or not the input was a single value or
        a sequence) of longitude and latitude in radians.
    """
    x, y, z = sph2cart(lon, lat)
    return cart2sph(-x, -y, -z)