Frequency-domain criteria of robust stability: Discrete-time and continuous-time systems,a unified approach

This paper is concerned with the stability and robust stability of linear discrete-time and continuous-time systems. The characteristic polynomials of linear systems are transformed into the general polynomials of discrete-time systems, and similarly to the hodogram of the discrete-time system, the stability and the robust stability for the general characteristic polynomials with parameter uncertainty are analysed by using the zero exclusion method, where the order of the system is not used specifically a condition for a stability.