MATLAB: Does a block mask in the model have ‘???’ on it and why do I get an error when I simulate the model containing such a block in Simulink

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When I drag a block into a model, the block mask has '???' on it and when I try to simulate the model I receive an error. For example, in the case of the "Analog Filter Design" block from the Signal Processing Toolbox, I receive the following error:

 Error in 'mymodel/Analog Filter Design': Initialization commands cannot be evaluated.  MATLAB error message: Error using ==> feval
 Undefined command/function 'butter'.

Best Answer

This problem occurs if your installation of MATLAB/Toolboxes is missing any files. In the example case described above, the Filter Design Toolbox installation is missing some files. In particular, it is missing the "butter.m" file.

To work around this issue, uninstall and re-install the toolbox that is missing the files.

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MATLAB: Suggestions for highpass filter design in Matlab

Yes, that looks fine as long as you realize that you have essentially an allpass filter since you are such a low stopband frequency

d = fdesign.highpass('Fst,Fp,Ast,Ap',0.5,0.6,40,1,500);
Hd = design(d,'butter');
fvtool(Hd)

You can also use butter() to design the filter in the analog domain directly in radians/second.

   N = 30;
   [B,A] = butter(N,pi,'high','s');

MATLAB: Error While Using the butter() function for IIR Butterworth filter design

I don't see where you are using butter() at all in the code you have posted here. This is an FIR filter design. Did you copy and paste the wrong code?

At any rate, do not name a script, or variable the same name as an exisiting MathWorks' function. If you really have a script named butter.m on your path (E:\Academics\6th Sem\DSP Lab\Exp-8\butter.m) , then rename that to something like my_butter.m, anything but butter. Then enter

>>which butter

and make sure you get something like:

matlab\toolbox\signal\signal\butter.m

returned.

Best Answer

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MATLAB: Suggestions for highpass filter design in Matlab

MATLAB: Error While Using the butter() function for IIR Butterworth filter design

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