
An object of the intraclass module defines a zero mean multivariate Gaussian distribution by its covariance matrix :math:`\Sigma` as 

.. math::
    
    \Sigma_{ij} = \begin{cases}
        \sigma^2, &\text{ if } i=j\\
        \rho\sigma^2, &\text{ if } (i,j) \in E \\
    \end{cases}



and :math:`\Sigma^{−1}_{ij} = 0 \text{ if } (i, j) \in  E \text{, where } \sigma^2 > 0  \text{ and } \rho \in [0, 1]` denote the variance and correlation coefficient, respectively.
Using an object id of this module in the ``parameters_id`` field of the ``data`` section requires that ``graph_id`` represents a decomposable graph.

