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Asked by Venkatapathi on 12 Feb 2013

Hi..

i am using MATLAB R2007 version in my PC.

i tried to define a transfer function from the following command..

a = tf([5],[0.8 1])

but my command window is showing an error like......

" Undefined function or method 'tf' for input arguments of type 'double'."

requesting you to help me on this issue...

Regards venkatapathi.p

Answer by Jan Simon on 12 Feb 2013

Accepted answer

The error message is clear: "Undefined function or method 'tf' for input arguments of type 'double'." This mean, that there is no TF function defined for doubles. Even clearing will not change this. The found @dfilt\tf function is obviously defined for dfilt objects.

The call `a = tf([5],[0.8 1])` is only possible, if you have the Control System Toolbox, see: http://www.mathworks.com/help/control/ref/tf.html

Answer by Azzi Abdelmalek on 12 Feb 2013

Edited by Azzi Abdelmalek on 12 Feb 2013

Try

clear tf a = tf([5],[0.8 1])

% You, probably used **tf** as a variable in your script, or you don't have a **system control** toolbox

Show 5 older comments

Azzi Abdelmalek on 12 Feb 2013

Exact. Then, what does mean

"C:\Program Files\MATLAB\R2007\toolbox\signal\signal\@dfilt\tf.m.

I mean, tf can be defined differently for two toolbox?

Answer by Sai Sandeep padala on 14 Mar 2013

but what if you have a licensed control tool box and you still get the same error

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