bugGNU Octave - Bugs: bug #51657, [octave-forge] (signal) gausswin...


bug #51657: [octave-forge] (signal) gausswin produces slightly wrong result

Submitted by:  None
Submitted on:  Fri 04 Aug 2017 11:55:32 AM UTC  
Category: Octave Forge PackageSeverity: 3 - Normal
Priority: 5 - NormalItem Group: Inaccurate Result
Status: ConfirmedAssigned to: None
Originator Name: Håkon A. HjortlandOriginator Email: -unavailable-
Open/Closed: OpenRelease: 4.0.0
Operating System: GNU/Linux

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Fri 11 Aug 2017 08:27:18 PM UTC, comment #3:

Ok, the last one is just weird. Matlab documentation mentions that N (M in the octave version) must be a positive integer. So the warning and rounding is not unexpected. but the fact that it accepts an array is odd, and odd results come about:

best as I can guess from the formula on the help page is that there's a matrix multiplication or division that is allowed to occur

I don't think that is at all intended. and it's not documented. So I'm going to ignore it and leave it as an error in octave for now unless matlab documentation changes.

Nicholas Jankowski <nrjank>
Fri 11 Aug 2017 06:41:52 PM UTC, comment #2:

checking the current tests in octave's gausswin, the following expect to produce errors, but don't in Matlab:

will include these in updated sets of tests

Nicholas Jankowski <nrjank>
Fri 11 Aug 2017 06:35:56 PM UTC, comment #1:


matlab 2017a:

Octave 4.2.1, signal 1.3.2, without your suggested change

Octave 4.2.1, signal 1.3.2, after making your suggested change to gausswin:

so there would be a few other compatibility wrinkles to work out. I'll try to generate some tests that a patch can be worked against.

Nicholas Jankowski <nrjank>
Fri 04 Aug 2017 11:55:32 AM UTC, original submission:

This is less pronounced for normal window lengths, though.

Looking at the algorithms section at
it seems that in signal-1.3.2/gausswin.m in the line
the expression a/m should be changed to a/(m-1).



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    Follow 3 latest changes.

    Date Changed By Updated Field Previous Value => Replaced By
    Fri 11 Aug 2017 08:29:08 PM UTCmtmillerStatusNone=>Confirmed
      Summarygausswin produces slightly wrong result=>[octave-forge] (signal) gausswin produces slightly wrong result
    Fri 11 Aug 2017 06:35:56 PM UTCnrjankCarbon-Copy-=>Added mtmiller

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