def getTOFgammaDeriv(dsp):
    """get derivatives of TOF peak profile gamma wrt X, Y & Z
    
    :param float dsp: d-spacing of peak
    
    :returns: list getTOFgammaDeriv: d(gam)/dX & d(gam)/dY
    
    """
    return dsp, dsp ** 2, 1.0
