Discrete Laplacian Distribution

docs/tutorial:stats:discrete_dlaplace

Defined over all integers for $a > 0$

Thus,

μ_{n}^{'} = M^{(n)} (0) = [1 + (- 1)^{n}] Li_{- n} (e^{- a})

where $Li_{- n} (z)$ is the polylogarithm function of order $- n$ evaluated at $z .$

h [X] = - lo g (tanh (\frac{a}{2})) + \frac{a}{sinh a}

Implementation: scipy.stats.dlaplace