def getTOFsigDeriv(dsp):
    """get derivatives of TOF peak profile sigma^2 wrt sig-0, sig-1, & sig-q
    
    :param float dsp: d-spacing of peak
    
    :returns: list getTOFsigDeriv: d(sig0/d(sig-0), d(sig)/d(sig-1) & d(sig)/d(sig-q)
    
    """
    return 1.0, dsp ** 2, dsp ** 4, dsp
