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Topic: Butterworth filter error
Replies: 1   Last Post: Nov 15, 2012 1:14 PM

 Messages: [ Previous | Next ]
 Ha Posts: 93 Registered: 11/30/09
Re: Butterworth filter error
Posted: Nov 15, 2012 1:14 PM

"Jai Abhishekh " <abhishekh236@gmail.com> wrote in message <k837rf\$hs8\$1@newscl01ah.mathworks.com>...
> Hello,
>
> I think I may have the most singular of problems.
> As everytime I try to run the butter filter, I get an error message saying
>

> >> butter(3,1)
> Error using butter (line 41)
> The cutoff frequencies must be within the interval of (0,1).
>
> Or
>
> iirchk() error.
>
> The code works well on other machines.

[z,p,k]=butter(n,Wn)
[z,p,k] = butter(n,Wn,'ftype')
[b,a]=butter(n,Wn)
[b,a]=butter(n,Wn,'ftype')
[A,B,C,D]=butter(n,Wn)
[A,B,C,D] = butter(n,Wn,'ftype')
[z,p,k]=butter(n,Wn,'s')
[z,p,k] = butter(n,Wn,'ftype','s')
[b,a]=butter(n,Wn,'s')
[b,a]=butter(n,Wn,'ftype','s')
[A,B,C,D]=butter(n,Wn,'s')
[A,B,C,D] = butter(n,Wn,'ftype','s')

What you need is to read the help doc.

butter(3,1) is a all-pass filter, a meaningless filter.

Date Subject Author
11/15/12 Jai Abhishekh
11/15/12 Ha