Output feedback compensation in multivariable systems

The question of dynamic feedback compensation in linear multi-variable systems is considered from a frequency domain point of view. Two related approaches to this problem are presented, both of which employ "dual relatively prime factorizations"; i.e. either R(s)P(s)-1 or P(s)-1R(s), of the transfer matrix, T(s), of the system. The first approach employs the notion of the "eliminant matrix" of two relatively right prime (r.r.p.) polynomial matrices, such as R(s) and P(s), while the second uses the properties of the class of unimodular matrices which "reduce" the composite matrix [R(s) P(s)] to an upper right identity, [1 0].