Nyquist analysis is a frequency response method for
determining absolute and relative stability of closed-loop control systems. Most
other methods, such as the Routh-Hurwitz criterion, can only determine absolute
stability, and they require that the characteristic equation is a finite
polynomial in *s*. Additionally, in the presence of delays in the system,
these other methods only yield approximate information regarding system
stability. In contrast, Nyquist analysis yields exact information about both
absolute and relative stability of the system, even in the presence of
delays.

See the *Embed Common Tasks Tutorial* at Altair
Community Documentation for examples of Nyquist analysis of stable and
unstable type 0 and 1 systems.

**To generate a Nyquist
plot**

1. Prepare the system for linearization.

2.
Choose **Analyze** **>** **Nyquist Response** to generate a Nyquist
plot.

3. Resize or zoom in on the plot for better viewing.