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

 
 

bug #43506: fir1 returns completely wrong results

Submitted by:  John <jcoppens>
Submitted on:  Fri 31 Oct 2014 03:14:30 AM UTC  
 
Category: LibrariesSeverity: 3 - Normal
Priority: 5 - NormalItem Group: Incorrect Result
Status: DuplicateAssigned to: None
Originator Name: JohnOpen/Closed: Closed
Release: 3.8.1Operating System: GNU/Linux

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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>
Project Administrator
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
    Fri 31 Oct 2014 04:27:32 PM UTCmtmillerStatusNone=>Duplicate
      Open/ClosedOpen=>Closed
      Dependencies-=>Depends on bugs #42763
    Fri 31 Oct 2014 03:14:30 AM UTCjcoppensAttached 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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