Erdem Correlation Coefficient

[Luiscri]

I think there is a little slip when calculating Erdem Correlation coefficient.

Coefficient is calculated like this:

coefficient = a_12/(len(array_1) * a_1 * a_2)

but reading this paper I think that it should be calculated like:

coefficient = a_12/((len(array_1)-1) * a_1 * a_2)

Moreover, I don't get the point of calculating the weight as (coefficient + 1)/2. Could you please explain me the meaning of that last step?