How to write a Transfer Function

I am trying to setup understand how to setup a transfer function, I input:

>> num = [1 1];

>> den = [1 2 1 5];

>> system = tf(num,den)

And expect the below answer but I keep getting an error message after inputting the system line:

'tf' requires one of the following:

Control System Toolbox

DSP System Toolbox

Model Predictive Control Toolbox

Signal Processing Toolbox

>>Transfer function: s + 1 ------------------- s^3 + 2 s^2 + s + 5

Any help would be appreciated

[Suttirak]

Open=tf([500],[1 32 340])

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 get a warning, it means that the toolbox is not installed.

[Alex yarker]

I got a warning message so I downloaded the Control Toolbox, the formulas now work as expected and I've stopped tearing my hair out, thanks very much.

[Ameer Hamza]

I am glad to be of help!!!