MATLAB: Transfer function ‘tf’

Question

Hi, in Matlab R2015b, I used the commando ' tf ' for the transfer function. When I run the script where I used it, I get an error message ' undefined function or variable 'tf' '. How do we get or create this function 'tf' ? I thought it was an inherent function of matlab. Thank you.

Answer 1

http://www.mathworks.com/help/control/ref/tf.html Control System Toolbox

http://www.mathworks.com/help/signal/ref/tf.html Signal Processing Toolbox

http://www.mathworks.com/help/mpc/ref/tf.html Model Predictive Control Toolbox

You need one of those three.