tf function doesn't work

when I try to use tf function this is what I get :

>> s = tf('s')

Unrecognized function or variable 'tf'.

Did you mean:

>> s = tfe('s')

[lounis chehrit]

It seems that the Control system toolbox is not installed !

You have to install It first !

Answer 1

[Ameer Hamza]

You need to have the control system toolbox: https://www.mathworks.com/help/control/index.html for using tf() function. It seems that you haven't installed this toolbox. Check the output of

ver control

If you have the toolbox installed, it will display the version of toolbox otherwise you don't have the toolbox.

[EL BIARI AYOUB]

Thank you very much !

[Erick Hernán Huillca Apaza]

I have it, but it seems : Warning: No properly formatted Contents.m file was found for 'control'.

> In ver (line 58) .................. at the final

[Walter Roberson]

You might need to reinstall .

[Fernanda]

Muchas gracias!!

Answer 2

[Nasreddine]

clear all ;
close all ;
clc ;

s=tf('s');
G=0.8/(0.5*s+1);
H=feedback(G,1);
step(H);
grid

●

[Walter Roberson]

I do not understand how this answers the question about tf() not being found?