Undefined function 'tf' for input arguments of type 'char'.

Hey everyone,

so I need to do some aerospace homework. I am running R2019a.

I type in: s = tf('s') and i get the error:

Undefined function 'tf' for input arguments of type 'char'.

can someone please help me?!

Thanks so much!

Answer 1

[Star Strider]

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

This:

ver('control')

will tell you if you have it. If you do, you will get something similar to:

-----------------------------------------------------------------------------------------------------
MATLAB Version: 9.7.0.1261785 (R2019b) Update 3
MATLAB License Number: #####
Operating System: Microsoft Windows 10 Pro Version 10.0 (Build 17763)
Java Version: Java 1.8.0_202-b08 with Oracle Corporation Java HotSpot(TM) 64-Bit Server VM mixed mode
-----------------------------------------------------------------------------------------------------
Control System Toolbox                                Version 10.7        (R2019b)

If you do not, a different message will appear.

The solution is to license, download and install the Control System Toolbox.

[Adam Danz]

Ha! I wasn't aware of that function! What a poor function name.

https://www.mathworks.com/help/control/ref/tf.html

Note that there are tf() function defined in the signal processing toolbox

https://www.mathworks.com/help/signal/ref/tf.html

Model Predictive Control toolbox

https://www.mathworks.com/help/mpc/ref/mpc.tf.html

DSP system Toolbox

https://www.mathworks.com/help/dsp/ref/dsp.channelizer.tf.html

https://www.mathworks.com/help/dsp/ref/dsp.notchpeakfilter.tfnotchpeakfilter.html

[Star Strider]

It’s been part of the Control System Toolbox since I first started using it.

I guess I’m just used to it after 25 years.

[Adam Danz]

+1

[Star Strider]

Thank you!