Another related use of the complex plane is with the Nyquist stability criterion.

The Nyquist stability criterion can now be found in all textbooks on feedback control theory.

Similarly, the Nyquist stability criterion also indicates instability but is silent about oscillation.

Modern books on feedback control theory quite frequently use the argument principle to serve as the theoretical basis of the Nyquist stability criterion.

It can be viewed as a generalization of the Nyquist stability criterion for linear time-invariant (LTI) systems.

The Nyquist stability criterion for oscillation is that the product of the stage gain multiplied by the transfer function of the inadvertent feedback network is greater than 1.

Bode plot, Nyquist stability criterion, Nichols plot, and root locus are the usual tools for SISO system analysis.

The Nyquist stability criterion developed by Harry Nyquist of Bell Laboratories can be used to study the stability of feedback amplifiers.

Ashby used his state counting measure of variety to describe stable states and produced the "Good Regulator" theorem which requires internal models for self-organized endurance and stability (e.g. Nyquist stability criterion).

The Nyquist stability criterion, discovered by Swedish-American electrical engineer Harry Nyquist at Bell Telephone Laboratories in 1932, is a graphical technique for determining the stability of a system.

In modern control theory textbooks, the Cauchy argument principle is quite frequently used to derive the Nyquist stability criterion, which can be used to predict the stability of negative feedback amplifier and negative feedback control systems.

Later, in 1970, Conant working with Ashby produced the Good Regulator theorem which required autonomous systems to acquire an internal model of their environment to persist and achieve stability (e.g. Nyquist stability criterion) or dynamic equilibrium.

Assessment of the stability of a closed-loop negative feedback system is done by applying the Nyquist stability criterion to the Nyquist plot of the open-loop system (i.e. the same system without its feedback loop).