rlocus throws up error

The root locus is not plotted and I get an error message as follows:

"NaN/Inf breakpoint hit for rlocusplot.m on line 83.

83 src = repmat(handle(NaN),nsys,1);"

For example,

>> sys = tf([2 5 1],[1 2 3]);

>> rlocus(sys)

Answer 1

[Star Strider]

Something else is wrong somewhere. I have no idea as to suggesting where to look for the problem.

The example code works here:

sys = tf([2 5 1],[1 2 3]);
rlocus(sys)

First, see if closing and then re-starting MATLAB solves it.

.

[M Prabhu]

Restarting Matlab solved the problem. But I have no idea why it happened in the first place. Thank you!

[Star Strider]

I am happy that you got that sorted!

(I have no idea, either. I never encountered a similar situation with the Control System Toolbox, however re-starting MATLAB has solved similar problems in my experience.)

As always, my pleasure!

.

Answer 2

[Paul]

Seems to work fine:

sys = tf([2 5 1],[1 2 3]);
rlocus(sys);

You might have a different function tf() or rlocus() that is shadowing the same from the Control System Toolbox. Do you see these results in repsonse to a which() command?

which tf -all

/MATLAB/toolbox/control/ctrlmodels/@tf/tf.m                     % tf constructor
/MATLAB/toolbox/control/ctrlmodels/@DynamicSystem/tf.m          % Shadowed DynamicSystem method
/MATLAB/toolbox/shared/controllib/engine/+ltipack/@tfdata/tf.m  % Shadowed ltipack.tfdata method
/MATLAB/toolbox/shared/controllib/engine/+ltipack/@ssdata/tf.m  % Shadowed ltipack.ssdata method
/MATLAB/toolbox/mpc/mpc/@mpc/tf.m                               % Shadowed mpc method
/MATLAB/toolbox/ident/ident/@idParametric/tf.m                  % Shadowed idParametric method
/MATLAB/toolbox/shared/controllib/engine/@StaticModel/tf.m      % Shadowed StaticModel method

which rlocus -all

/MATLAB/toolbox/control/ctrlobsolete/rlocus.m
/MATLAB/toolbox/control/ctrldesign/@DynamicSystem/rlocus.m                % Shadowed DynamicSystem method
/MATLAB/toolbox/shared/controllib/engine/+ltipack/@ltidata/rlocus.m       % Shadowed ltipack.tfdata method
/MATLAB/toolbox/shared/controllib/graphics/@resppack/@ltisource/rlocus.m  % Shadowed resppack.ltisource method

[M Prabhu]

Hi Paul. Unfortunately, I restarted Matlab before I could try your solution. After restarting, rlocus worked fine. Thank you !