editing a nyquist figure
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mona faraji
on 28 Mar 2011
Commented: Nick Dienemann
on 24 May 2022
How can I edit a nyquist figure or how can I plot a nyquist diagram using MATLAB such that it just consists positive frequencies and not negative ones ?
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Accepted Answer
Teja Muppirala
on 30 Mar 2011
Run the nyquist command as usual:
nyquist([1],[1 2 1])
Then if you right click on the axes (the white part), a context menu will pop up and in the third option you can select not to show the negative frequencies.
More Answers (2)
Nick Dienemann
on 24 May 2022
You can use the following code to turn of plotting of the negative frequencies within your code. Spares you the time to disable them manually in the plot window as suggested by Teja.
num= [-1 1]; %numerator
den= [2 2]; %denominator
G = tf(num,den)
%-------------- Nyquist diagramm --------------------------
plotoptions= nyquistoptions('cstprefs') ; % default options
plotoptions.ShowFullContour = 'off'; % exclude negative frequencies
nyquist(G,plotoptions)
1 Comment
Nick Dienemann
on 24 May 2022
find https://de.mathworks.com/help/control/ref/nyquistoptions.html for more options concerning the nyquist plot.
Arnaud Miege
on 28 Mar 2011
" nyquist(sys,w) explicitly specifies the frequency range or frequency points to be used for the plot. To focus on a particular frequency interval, set w = {wmin,wmax}. To use particular frequency points, set w to the vector of desired frequencies. Use logspace to generate logarithmically spaced frequency vectors. Frequencies should be specified in rad/sec."
Either specify a positive frequency interval or a vector of positive frequencies.
HTH,
Arnaud
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