def calc_cR ( Q2 , sigma ) : return Q2 * np . exp ( np . sum ( np . log ( sigma ** 2 ) ) / sigma . shape [ 0 ] )
fit r like formula model in python without intercept
Returns the cR statistic for the variogram fit ( see [ 1 ] ) .
def calc_cR(Q2, sigma):
    """Returns the cR statistic for the variogram fit (see [1])."""
    return Q2 * np.exp(np.sum(np.log(sigma**2))/sigma.shape[0])