I am trying to make the Nyquist plot of the function $\frac{200}{(s+1)(s+2)(s+3)}$ as below. However, I would like to see mark the critical point (-1, 0) on the plot so we can see clearly whether the plot encircles the point or not. I am curious to know how you usually do this? How to show the critical point easily?

NyquistPlot[TransferFunctionModel[200/((s + 1)*(s + 2)*(s + 3)), s]]

closed as off-topic by C. E., MarcoB, Bob Hanlon, m_goldberg, Jens Jul 24 '17 at 1:07

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  • 2
    $\begingroup$ You can use the Epilog option: Epilog -> {Red, PointSize[Large], Point[{-1, 0}]} – just add this as the last argument of NyquistPlot. NyquistPlot has all the options that Graphics has. Note that Epilog is documented as an option under Graphics and not under NyqustPlot. It also has its own page in the documentation. $\endgroup$ – C. E. Jul 23 '17 at 22:39
  • 1
    $\begingroup$ Also, you can focus on the critical point with PlotRange, as in: NyquistPlot[TransferFunctionModel[200/((s + 1)*(s + 2)*(s + 3)), s], PlotRange -> {{-5, 1}, {-1, 1}}, Epilog -> {Red, PointSize[Large], Point[{-1, 0}]}] $\endgroup$ – aardvark2012 Jul 23 '17 at 23:18

Just to get an answer on record.

NyquistPlot[TransferFunctionModel[200/((s + 1)*(s + 2)*(s + 3)), s], 
  Epilog -> {Red, AbsolutePointSize[5], Point[{-1, 0}]}]



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