RMmult is a multivariate covariance model which depends on
up to 10 submodels $C_0, C_1, ..., C_10$.
In general, realizations of the created RMmodel are pointwise
product of independent realizations of the submodels.
In particular, if all submodels are given through a covariance
function, the resulting model is defined through its covariance
function, which is the product of the submodels' covariances.
The global parameters scale,Aniso,proj of RMmult
are multiplied to the corresponding parameters of the submodels
(from the right side).
In case that all submodels are given through a covariance function,
the global parameter var of RMmult
is multiplied to the product covariance of RMmult.