def mod_Goodman_Fos(sa, sm, Se, Sut):
    """
    Computes the mod Goodman relation factor of safety
    :param sa: alternating stress
    :param sm: midrange stress
    :param Se: Endurance strength
    :param Sut: Ultimate tensile strength
    :return: factor of safety
    """

    n_inv = sa/Se + sm / Sut

    return 1/n_inv