Generic function for extracting model-implied covariance matrices, either
from the MCMC output, or from the simulated model. Details about the
function's behavior can be found in  covmat.fsvdraws
(the function invoked when applied to MCMC output) or
covmat.fsvsim (the function invoked when applied to a
simulated model.
covmat(x, ...)Structure containing the model-implied covariance matrix.
An object of class fsvdraws or fsvsim.
Arguments to be passed to methods.
Other generics: 
cormat()