MATLAB: I can’t use function tf() and bode()

Control System Toolboxfoldingsymbolic

 when i try a example: 
>> H = tf([1 0.1 7.5],[1 0.12 9 0 0]);
bode(H)
Undefined function 'tf' for input arguments of type 'double'.

as it appears on the error, I do not know what to fix desire to help people. thanks a lot

Best Answer

tf() is in the Control Systems Toolbox. That is not included in the Professional or Academic licenses, but is included in the Student Version license... but is not installed by default with the Student license.

Related Solutions

MATLAB: Bode() magnitude

Magnitude and phase outputs of bode are 3-D arrays, for representing multi-input multi-output systems. The first two dimensions correspond to the number of inputs and outputs, the third dimension corresponds to the number of frequency points. In your case you have a single-input single-output system, so size(mag) is 1 1 n, where n is the number of frequency points.

To get a standard bode plot you can just do

bode(sys)

If you want access to mag and phase as regular vectors, just do

mag=squeeze(mag)

All of this is covered in the doc.

Arkadiy

MATLAB: Extracting values from bode()

Hi,

The NY and NU sizes are based on the number IOs (inputs and outputs) your system has and would be fixed. You can compute the response at various frequencies with the resulting mag and phase being a NY-by-Nu-by-Nw vector where Nw is the number of frequency points. If you are trying to extract data at more frequencies or a specific set of frequencies you can specify the frequency vector explicitly

[mag,phase,wout] = bode(sys,win)

In this case win = wout. For example, evaluating 100 points equally logrithmic spaced points between 10^-1 and 10 would be done has follows

[mag,phase,wout] = bode(sys, logspace(-1,1,100))

Best Answer

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MATLAB: Bode() magnitude

MATLAB: Extracting values from bode()

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