Function File: hartley_entropy (P)

Compute the Hartley entropy using Reyni entropy of order 0, for the given probability distribution.

H\alpha(P(x)) = log\sum_i (Pi(x)^\alpha)/(1-\alpha)

special-cases include, and when alpha=0, it reduces to Hartley entropy.

Hartley entropy H0(X) = log|X|, where X=n(P), cardinality of P, the pdf of random variable x.

                   hartley_entropy([0.2 0.3 0.5])
                   ⇒   ans = 1.0986