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P = nyquistoptions
P = nyquistoptions('cstprefs')
P = nyquistoptions returns the default options for Nyquist plots. You can use these options to customize the Nyquist plot appearance using the command line.
P = nyquistoptions('cstprefs') initializes the plot options with the options you selected in the Control System Toolbox Preferences Editor. For more information about the editor, see Toolbox Preferences Editor in the User's Guide documentation.
The following table summarizes the Nyquist plot options.
| Option | Description |
|---|---|
| Title, XLabel, YLabel | Label text and style |
| TickLabel | Tick label style |
| Grid | Show or hide the grid Specified as one of the following strings: 'off' | 'on' Default: 'off' |
| XlimMode, YlimMode | Limit modes |
| Xlim, Ylim | Axes limits |
| IOGrouping | Grouping of input-output pairs Specified as one of the following strings: 'none' |'inputs'|'output'|'all' Default: 'none' |
| InputLabels, OutputLabels | Input and output label styles |
| InputVisible, OutputVisible | Visibility of input and output channels |
| FreqUnits | Frequency units, specified as one of the following strings:
Default: 'rad/s' You can also specify 'auto' which uses frequency units rad/TimeUnit relative to system time units specified in the TimeUnit property. For multiple systems with different time units, the units of the first system are used. |
| MagUnits | Magnitude units Specified as one of the following strings: 'dB' | 'abs' Default: 'dB' |
| PhaseUnits | Phase units Specified as one of the following strings: 'deg' | 'rad' Default: 'deg' |
| ShowFullContour | Show response for negative frequencies Specified as one of the following strings: 'on' | 'off' Default: 'on' |
| ConfidenceRegionNumberSD | Number of standard deviations to use to plotting the response
confidence region (identified models only). Default: 1. |
| ConfidenceRegionDisplaySpacing | The frequency spacing of confidence ellipses. For identified
models only. Default: 5, which means the confidence ellipses are shown at every 5th frequency sample. |
This example shows how to create a Nyquist plot displaying the full contour (the response for both positive and negative frequencies).
P = nyquistoptions; P.ShowFullContour = 'on'; h = nyquistplot(tf(1,[1,.2,1]),P);
getoptions | nyquist | nyquistplot | setoptions

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