How can I fix this error defining 's'.

Everytime I type s=tf('s') appears the following error: Undefined function 'tf' for input arguments of type 'char'. How I can fix this error?

Thanks, Sergio.

Answer 1

[Image Analyst]

It's possible you don't have the Signal Processing Toolbox, which has the tf() function in it. Type ver on the command line to see if you have that toolbox.

[FRANCESCO BAROZZI]

i have the Signal Processing Toolbox in my matlab.

command s=tf('s') stop to work after a windows update! After this S.O. update i opened matlab and prompted me to insert my license , like the first time i run the program. i think is a conflict betwen matlab and window 10 !!!

how i can fix?

[Image Analyst]

You can call the Mathworks for fast and free telephone help - that's the fastest way believe it or not. Did I mention that it was free, so you have no excuse not to call them?

[John BG]

who is the question originator, Mr Sergio Muñoz or Mr Francesco Barozzi?

[Jan]

@John BG: As you can see, Sergio asked the question in 2016, and Francesco posted a concerning question in the comment section now.

Answer 2

[John BG]

If you key in the polynomials directly

tf([1 -2 1],[3 -.4] )

ans =

    s^2 - 2 s + 1
    -------------
      3 s - 0.4

tf works fine.

Perhaps you mean

tf([1 0],1)

ans =

    s

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thanks in advance

John

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