Problem using tf to perform a transfer function.

I was trying to mimic an m-script file for completing a transfer function from my textbook. I ran into an issue where I receive an error "Undefined functin 'tf' for input arguments of type 'double'."

My code is as follows:

numg=[6 0 1];

deng=[1 3 3 1];

sysg=tf(numg,deng);

Undefined functin 'tf' for input arguments of type 'double'.

It is important to know that the code comes from the textbook. Could I be missing a package?

Answer 1

[Star Strider]

You need to have the Control System Toolbox licensed and installed.

With that, the code works appropriately —

numg=[6 0 1];
deng=[1 3 3 1];
sysg=tf(numg,deng)

sysg =
 
        6 s^2 + 1
  ---------------------
  s^3 + 3 s^2 + 3 s + 1
 
Continuous-time transfer function.

.

[Leaysia Lampkin]

Thank you

[Star Strider]

As always, my pleasure!

Answer 2

[Sam Chak]

Hi @Leaysia Lampkin

If you are unable to obtain the Control System Toolbox, many useful MATLAB-compatible functions can still be executed on Octave Online. These functions include ss, tf, zpk, damp, pole, zero, rlocus, bode, nyquist, pid, feedback, minreal, dcgain, step, initial, impulse, lsim, place, lqr, lyap, etc.