one SAMPLED-DATA CONTROL SYSTEMS 
are even rational polynomials of the index, can be evaluated by applying 
the Poisson summation rule. The theory of sampled-data systems in 
which two alternate forms of the transform of a sampled variable is useful 
in this case. These applications of sampled-data theory all arise because 
sampled-data systems are described by difference equations and z trans- 
forms are applicable to the solution of these equations. 
