Error simple program PID

Hello, I doing a pid project I have everything correct but this error come up what I should do?

Answer 1

[JOJO]

in my second compute it works, however I dont know how to find the tooboxes

[Mischa Kim]

Type

which -all syms

and you should get something like

C:\Program Files\MATLAB\R2013b\toolbox\symbolic\symbolic\syms.m

Answer 2

[Mischa Kim]

Interesting. The code is just fine.

Try this: copy-and-paste the code from your question above and paste it into the MATLAB command window. Execute.

[Mischa Kim]

I assume you have the Symbolic Toolbox licensed?

Also, please post comments as comments.

Answer 3

[JOJO]

I tried it give me this error I dont know why

Answer 4

[David Sanchez]

I tried your code (copy-paste) and it works. Make sure you have the Symbolic Math toolbox:

Start (bottom left corner)-> Toolboxes

You should see the all the toolboxes of your system, if you do not locate the Symbolic Math toolbox, you can not use

syms

Answer 5

[JOJO]

I used control theory it worked.

Thanks Davi

Answer 6

[Carla]

Is there a reason you need to do this with syms? At least in the code you showed, it doesn't look like you are using any Symbolic Toolbox functionality. You can achieve the same exact result using only Control System Toolbox as follows:

num=1; % Numerator
den=[1,3,1]; % Denominator

G=tf(num,den); % Transfer Function

H=1; % Negative Feedback Loop with Unity Feedback

Kp=1; % Increment these three varaibles to give desired output
Ki=0;
Kd=0;

C=pid(Kp,Ki,Kd); % Controller Function

T=feedback(C*G,H); % C in series with G with negative feedback H

step(T)  % Step Response with Controller

If there is some reason elsewhere in your program that you need syms functionality, I suppose this won't solve your problem!