nyquist_extended

Nyquist plot with closure at infinity v.1.2.1

Version 1.2.1 (3.34 KB)
177 Downloads
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31 Mar 2026

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This (didactic) function takes a transfer function (rational or with time delay) as input and calculates the Nyquist contour in the s-plane while bypassing the poles located on the imaginary axis.
Then, this Nyquist contour is used to perform the mapping by taking into account the contributions of the poles and zeros.
The delay is accounted considering its impact on the phase.
The resulting output is the Nyquist plot in the w-plane with the closure at infinity. It also provides information about the poles located on the imaginary axis, including their impact in terms of angles on the w-plane.

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Cite As

Diego Caccavo (2026). nyquist_extended (https://www.mathworks.com/matlabcentral/fileexchange/129319-nyquist_extended), MATLAB Central File Exchange. Retrieved .

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General Information

MATLAB Release Compatibility

  • Compatible with R2021b and later releases

Platform Compatibility

  • Windows
  • macOS
  • Linux
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Version Published Release Notes
1.2.1

Fixed incorrect phase contribution for detour around imaginary-axis poles (removed unintended +π shift).
1.2

- Code cleanup
- The MATLAB Nyquist plot has been removed from the output graph
- A more rigorous approach for negative transfer constants has been used (line 88-92).

1.1

- Phase angle calculation has been corrected to works also with TF with positive zeros and/or negative transfer constants.
- The MATLAB Nyquist plot has been incorporated into the output graph, facilitating the verification of response accuracy.
1.0.4

Corrected output angles in case of negative transfer constant and only poles
1.0.3

Nyquist plot adjusted in case of no zeros and negative transfer constant
1.0.2

Improved plot for negative gain with only poles
1.0.1

Angles adjustment in case of dead time
1.0.0