def maxdiff(self):
        """
        m.maxdiff()   -- Compute maximum possible Euclidean distance to another motif.  (For normalizing?)
        """
        POW  = math.pow
        D = 0
        for i in range(self.width):
            _min = 100
            _max = -100
            for L in ACGT:
                val = POW(2,self.logP[i][L])
                if   val > _max:
                    _max  = val
                    _maxL = L
                elif val < _min:
                    _min  = val
                    _minL = L
            for L in ACGT:
                if L == _minL:
                    delta = 1-POW(2,self.logP[i][L])           #1-val
                    D = D + delta*delta
                else:
                    D = D + POW( POW(2,self.logP[i][L]), 2)    #0-val
        return(math.sqrt(D))
m.maxdiff()   -- Compute maximum possible Euclidean distance to another motif.  (For normalizing?)