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List of Nyquist plot options


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 and System Identification Toolbox Preferences Editor. For more information about the editor, see Toolbox Preferences Editor.

The following table summarizes the Nyquist plot options.

Option Description
Title, XLabel, YLabel Label text and style
TickLabelTick label style
Grid Show or hide the grid
Specified as one of the following values: 'off' | 'on'
Default: 'off'
GridColorColor of the grid lines
Specified as one of the following: Vector of RGB values in the range [0,1] | character vector of color name | 'none'. For example, for yellow color, specify as one of the following: [1 1 0], 'yellow', or 'y'.
Default: [0.15,0.15,0.15]
XlimMode, YlimModeLimit modes
Xlim, Ylim Axes limits
IOGrouping Grouping of input-output pairs
Specified as one of the following values: 'none' |'inputs'|'outputs'|'all'
Default: 'none'
InputLabels, OutputLabels Input and output label styles
InputVisible, OutputVisibleVisibility of input and output channels

Frequency units, specified as one of the following values:

  • 'Hz'

  • 'rad/second'

  • 'rpm'

  • 'kHz'

  • 'MHz'

  • 'GHz'

  • 'rad/nanosecond'

  • 'rad/microsecond'

  • 'rad/millisecond'

  • 'rad/minute'

  • 'rad/hour'

  • 'rad/day'

  • 'rad/week'

  • 'rad/month'

  • 'rad/year'

  • 'cycles/nanosecond'

  • 'cycles/microsecond'

  • 'cycles/millisecond'

  • 'cycles/hour'

  • 'cycles/day'

  • 'cycles/week'

  • 'cycles/month'

  • 'cycles/year'

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 values: 'dB' | 'abs'
Default: 'dB'
PhaseUnits Phase units
Specified as one of the following values: 'deg' | 'rad'
Default: 'deg'
ShowFullContourShow response for negative frequencies
Specified as one of the following values: 'on' | 'off'
Default: 'on'
ConfidenceRegionNumberSDNumber of standard deviations to use to plotting the response confidence region (identified models only).
Default: 1.
ConfidenceRegionDisplaySpacingThe 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);

Introduced in R2011a