Entropy of a discrete random variable with possible values $\{x_1, x_2, \dots , x_n\}$ and probability density function $P(X)$ is
$H(X) = \: – \sum\limits_{i=1}^{n}P(x_i) \log _bP(x_i)$
The value of $b$ gives the units of entropy. The unit for $b=10$ is
- bits
- bann
- nats
- deca
