Where Z ( ) {\displaystyle Z()} denotes z-Transform for the chosen sample time T {\displaystyle T} . There are many ways to directly design a digital controller D ( z ) {\displaystyle D(z)} to achieve a given specification.[1] For a type-0 system under unity negative feedback control, Michael Short and colleagues have shown that a relatively simple but effective method to synthesize a controller for a given closed-loop denominator polynomial P ( z ) {\displaystyle P(z)} and preserve (scaled) zeroes of the PTF B ( z ) {\displaystyle B(z)} is to use the design equation:[8]