def spin_factor(J, M, c):
    """
    Calculate spin factor(a) of kerr body

    Parameters
    ----------
    J : float
        Angular momentum in SI units(kg m2 s-2)
    M : float
        Mass of body in SI units(kg)
    c : float
        Speed of light

    Returns
    -------
    float
        Spin factor (J/(Mc))

    """
    return J / (M * c)