The control of linear time-invariant process models is considered. Systems
where there are single or multiple inputs and outputs are analysed using co
nventional frequency domain techniques. The use of influence functions whic
h are employed to affect the closed-loop characteristic equation of the sys
tem model is advocated. Minimization of the control effort required, while
generating a prescribed influence function is achieved, using input-output
measurements only. Illustrative studies are included for demonstration purp
oses.