New results about Morgan´s problem

Some aspects of the nonsquare Morgan´s problem are considered. In particular, it is shown that the condition given by J. Descusse et al. (1986) to solve this problem is not sufficient. It is also shown that the essential orders are not necessarily preserved in the static decoupling problem. A necessary and sufficient condition for static decoupling of a system without modifying the essential orders is given for the case k=p-1. where p is the number of outputs and k is the rank at infinity of the proper part of the interactor