def ccf(x, y, unbiased=True):
 cvf = ccovf(x, y, unbiased=unbiased, demean=True)
 return (cvf / (np.std(x) * np.std(y)))

def ccf ( x , y , unbiased = True ) : cvf = ccovf ( x , y , unbiased = unbiased , demean = True ) return ( cvf / ( np . std ( x ) * np . std ( y ) ) )
cross-correlation function for 1d parameters x .