ESDU 74020 is the second in an integrated group of seven that deal with methods of assessing the stability and response of linear systems. It considers methods of graphical presentation that provide the means of displaying the effects on the characteristics of the system of varying some of its parameters. The methods discussed are the root locus and the one parameter stability diagrams, which are alternative ways of showing how variations in one parameter affect the damping and frequency of the modes of motion, and the two parameter stability diagram which displays the effect on the system stability of varying two parameters and also shows the damping and frequency of the mode whose stability is of concern.
