def npqt(fmp, f0p, fmf0=4.88):
    """Calculate NPQt

    NPQt = (4.88 / ((fmp / f0p) - 1)) - 1

    :param fmp: Fm'
    :param f0p: F0'
    :param fmf0: Fv/Fm (default: 4.88)
    :returns: NPQ (float)
    """

    return (fmf0 / ((fmp / f0p) - 1)) - 1