def getTOFsig(ins, dsp):
    """get TOF peak profile sigma^2
    
    :param dict ins: instrument parameters with at least 'sig-0', 'sig-1' & 'sig-q'
      as values only
    :param float dsp: d-spacing of peak
    
    :returns: float getTOFsig: peak sigma^2
    
    """
    return ins['sig-0'] + ins['sig-1'] * dsp ** 2 + ins['sig-2'
        ] * dsp ** 4 + ins['sig-q'] * dsp
