('tf' requires one of the following) "tf commend is not working" HELP PLS!

this simple command doesn't work even though I've entered all commands correctly

thx for answers...

Answer 1

[M]

Your code is right, but you do not have the required toolbox. The function tf is part of the 4 toolbox listed in the error message. You have to install at least one of them to use tf.

[Mesut Yilmaz]

many thanks I installed the control system toolbox and it worked

Answer 2

[Supriya Joshi]

%poles and zeros num=[1 4 3]; den=[3 19 27 35]; z=tf(num,den) %z1=roots(num) %p1=roots(den) [z1,p1,k]=tf2zp(num,den) pzmap(z)