yuima.Output class is a class of the yuima-class it represents a map of a stochastic process
zt = g(theta, Xt, t) : R^{q x d x 1} -> R^{l1 x l2 x ...}
or an operator between two independent stochasic process:
zt = h(theta, Xt, Yt, t)
where Xt and Yt areobject of class yuima.model-class or yuima-class with the same dimension.