dPosterior.CatDirichlet: Density function of the posterior distribution of a "CatDirichlet" object
Description
Generate the the density value of the posterior distribution of the following structure:
$$pi|alpha \sim Dir(alpha)$$
$$x|pi \sim Categorical(pi)$$
Where Dir() is the Dirichlet distribution, Categorical() is the Categorical distribution. See ?dDir and dCategorical for the definitions of these distribution.
The model structure and prior parameters are stored in a "CatDirichlet" object.
Posterior density is the density function of Dir(pi|alpha).