entropy

fnElementType!Range entropy(Range)(Range r) if (isInputRange!Range)

Computes _entropy of input range r in bits. This function assumes (without checking) that the values in r are all in [0, 1]. For the entropy to be meaningful, often r should be normalized too (i.e., its values should sum to 1). The two-parameter version stops evaluating as soon as the intermediate result is greater than or equal to max.

ElementType!Range entropy(Range,  F)(Range r,  F max) if (isInputRange!Range &&
    !is(CommonType!(ElementType!Range,  F)  ==  void))

Ditto