External description for multivariable systems sampled in an aperiodic way

An external description for nonperiodically sampled multivariable linear systems has been developed. Emphasis is on the sampling period sequence, included among the variables to be handled. The computational procedure is simple and no use of polynomial matrix theory is required. This input/output description is believed to be a basic formulation for its later application to the problem of optimal control and/or identification of linear dynamical systems