Join Entropy

Joint Entropy is defined as below, which represent the join Entropy of \(X\) and \(Y\):

$$ H(A_X,A_Y) = \sum^{J-1}_{j=0} \sum^{K-1}_{k=0} p(x_j,y_k) \lg \left[ \frac{1}{p(x_j,y_k)} \right] $$