control.matlab.nyquist

control.matlab.nyquist(syslist, omega=None, plot=True, label_freq=0, arrowhead_length=0.1, arrowhead_width=0.1, color=None, *args, **kwargs)

Nyquist plot for a system

Plots a Nyquist plot for the system over a (optional) frequency range.

Parameters

  • syslist (list of LTI) – List of linear input/output systems (single system is OK)

  • omega (freq_range) – Range of frequencies (list or bounds) in rad/sec

  • Plot (boolean) – If True, plot magnitude

  • color (string) – Used to specify the color of the plot

  • label_freq (int) – Label every nth frequency on the plot

  • arrowhead_width (arrow head width) –

  • arrowhead_length (arrow head length) –

  • *args (matplotlib.pyplot.plot() positional properties, optional) – Additional arguments for matplotlib plots (color, linestyle, etc)

  • **kwargs (matplotlib.pyplot.plot() keyword properties, optional) – Additional keywords (passed to matplotlib)

Returns

  • real (array) – real part of the frequency response array

  • imag (array) – imaginary part of the frequency response array

  • freq (array) – frequencies

Examples

>>> sys = ss("1. -2; 3. -4", "5.; 7", "6. 8", "9.")
>>> real, imag, freq = nyquist_plot(sys)