Root Locus system description at given point not showing up

When I use rlocus(), clicking on a point simply displays the coordinates rather than the system information at that point (gain, damping ratio, etc). Additionally, 'grid on' gives an error.

g=tf([1],[1 24 84 80]);

rlocus(g)

Edit: Solved the problem. I was running the code in a live script, but it must be executed in Command Window.

[Paul]

Interesting. What happens if you run it in the Live Script, and then click the little arrow in the upper right corner of the figure in the Live script to open it in a figure window? Do the data tips work as expected in that case?

[Whitten Oswald]

Nope, that's how I was trying it (in the original screenshot). Same exact code and figure in Command Window works though.

Answer 1

[Pravarthana P]

Hi Whitten Oswald,

I understand that you are looking for the system information while hovering over the plot.

In MATLAB versions R2018b or later, the data cursor mode has been made as the built-in interactions. Since you are using R2021b, the data points should be enabled by default.

I tried reproducing the issue at my end and I could see the information datapoints enabled by default. One possible work around would be to customize your built-in interactions and add dataTipInteraction to the Interaction array.

Hope this helps you!!

[Whitten Oswald]

Thank you for your response.

I discovered the custom DataTips while trying to troubleshoot this problem, but hoped it wouldn't come to that. I'll look into doing this.

Answer 2

[Paul]

Is there any chance that you have some local version of rlocus() that is shadowing the Control System Toolbox? What is the output of

which rlocus -all

/MATLAB/toolbox/control/ctrlobsolete/rlocus.m
/MATLAB/toolbox/control/ctrldesign/@DynamicSystem/rlocus.m  % Shadowed DynamicSystem method

g=tf([1],[1 24 84 80]);
which rlocus(g)

/MATLAB/toolbox/control/ctrldesign/@DynamicSystem/rlocus.m  % tf method

[Whitten Oswald]

[Paul]

Well, it was worth a shot. I don't know what controls the datatips, or why you'd be having an issue with grid. It's still possible that there is a name clash of a function that is called from rlocus(g). Or it might be something else altogether.

[Whitten Oswald]

No worries, I appreciate you trying anyway. It doesn't seem to be a common problem for a lot of users, so I'll probably just try to implement the data tips manually as Pravarthana P suggested (if I can figure out how).

Thanks again.