bugGNU Octave - Bugs: bug #43506, fir1 returns completely wrong...

 
 

bug #43506: fir1 returns completely wrong results

Submitter:  John <jcoppens>
Submitted:  Fri 31 Oct 2014 03:14:30 AM UTC
   
 
Category:  Libraries Severity:  3 - Normal
Priority:  5 - Normal Item Group:  Incorrect Result
Status:  Duplicate Assigned to:  None
Originator Name:  John Open/Closed:  * Closed
Release:  * 3.8.1 Operating System:  * GNU/Linux
Fixed Release:  None Planned Release:  None
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Fri 31 Oct 2014 04:34:03 PM UTC, comment #2: 

Great Mike, and thanks! I'm trying to compile 3.8.2 as I write, but hit a needed update for glibc (submitted a bug on this).


John <jcoppens>
Fri 31 Oct 2014 04:27:32 PM UTC, comment #1: 

Thanks for your bug report. This regression has already been reported and fixed. If you are able to upgrade to Octave 3.8.2, you will get the correct results from the fir1 function. The original report was bug #42763 (interp1 regression).

Mike Miller <mtmiller>
Group Member
Fri 31 Oct 2014 03:14:30 AM UTC, original submission:  

Somewhat surprised when I submitted a simple bandpass filter to the fir1 function and got wrong results (according docs the fir1 should return a bandpass by default, which it did not, but even when specifying the filter type, the result was the same, i.e. wrong).

I then looked up the docs for Matlab docs and submitted the example to Octave:

octave:2> b = fir1(48,[0.35 0.65]);
octave:3> freqz(b,1,512)

The result from Matlab is in the first attachment, the result from Octave in the second. Maybe I'm doing something wrong here?
It seems the upper limit is more or less correct, but the lower limit is always at 0. Adding ", 'bandpass'" makes no difference.

Octave is version 3.8.1.

John <jcoppens>

 

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    Follow 6 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2014-10-31 mtmiller StatusNone Duplicate
        Open/ClosedOpen Closed
        Dependencies- Depends on bugs #42763
    2014-10-31 jcoppens Attached File- Added Screenshot - 10302014 - 09:55:41 PM.png, #32346
        Attached File- Added Screenshot - 10302014 - 09:56:13 PM.png, #32347
        Carbon-Copy- Added jcoppens

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