Computes the theoretical values of the mean, variance,
skewness and (excess) kurtosis vectors for the d-variate Generalized
Hyperbolic distribution \(\mathcal{GH}\left( \lambda
,\chi ,\psi ,\boldsymbol{\mu },\boldsymbol{\Sigma },\boldsymbol{\gamma }%
\right)\)
defined as
$$\mathbf{X}=\boldsymbol{\mu }+V\boldsymbol{\gamma }+\sqrt{V}\boldsymbol{%
\Sigma }^{1/2}\mathbf{Z}$$
where \(\mathbf{Z}\in \mathcal{N}\left( 0,\mathbf{I}_{d}\right)\),
\( V \geq 0\), is independent of \(\mathbf{Z}\), is a non-negative,
scalar-valued variate, which is Generalized Inverse Gaussian (scalar
valued GIG), \(V\in GIG\left( \lambda ,\chi ,\psi \right)\).