ABSTRACT
Implicit in our construction of design specifications such as those illustrated by Figures 10.2 and 10.3 is the assumption that the transfer functions can be prescribed independently in different frequency regions or that open-loop gain and phase can be independently manipulated. However, the requirement that the closed-loop system be stable imposes additional constraints on the transfer functions that relate the values of the functions in different frequency regions. These constraints will be referred to as analytic constraints because they result from the requirement that the transfer functions have certain analytic properties.
