('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)

Answer 3

[jean carlos]

por que me sale este error me podra ayudarme por favor

%% LGR

Gzl=tf(Numz,Denz,-1);

rlocus(Gzl); %LGR

axis([-1.5 1.5 -1.25 1.25]);

title('LGR');

>> jean

Unrecognized function or variable 'Numz'.

Error in jean (line 2)

Gzl=tf(Numz,Denz,-1);

Unrecognized function or variable 'Numz'

[Stephen23]

"Unrecognized function or variable 'Numz'"

Solution: define Numz.

Question: what do you expect Numz to be?

[Sam Chak]

@jean carlos, You need to specify the numerator and denominator coefficients ordered in descending powers of z.

Numz = [2, 0];
Denz = [4, 0, 3, -1];
Gzl  = tf(Numz, Denz, -1)

Gzl =
 
        2 z
  ---------------
  4 z^3 + 3 z - 1
 
Sample time: unspecified
Discrete-time transfer function.