bugGNU Octave - Bugs: bug #60427, [octave forge] (signal) decimate...

 
 

bug #60427: [octave forge] (signal) decimate function outputs divergent numbers

Submitter:  Paul Netsaver <netsaver>
Submitted:  Tue 20 Apr 2021 09:26:02 PM UTC
 
Category:  Octave Forge Package Severity:  3 - Normal
Priority:  5 - Normal Item Group:  Inaccurate Result
Status:  Confirmed Assigned to:  None
Originator Name:  Netsaver Paul Open/Closed:  * Open
Release:  * dev Operating System:  * Any
* Mandatory Fields

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Wed 21 Apr 2021 06:02:17 PM UTC, comment #1: 

Confirmed.

To me, this looks like a small missing feature of the Octave decimate function. According to https://www.mathworks.com/help/signal/ref/decimate.html, the Chebyshev filter order needs to be automatically reduced when the distortion is too large.

Mike Miller <mtmiller>
Project Administrator
Tue 20 Apr 2021 09:26:02 PM UTC, original submission:  

...\packages\signal-1.4.1\decimate.m

decimate(rand(1e4,1),1e3)
ans [Matlab 2016a]=
    0.5761
    0.4891
    0.4910
    0.5070
    0.5118
    0.4927
    0.4988
    0.5104
    0.5027
    0.5145

ans [Octave 6.2]=
  -6.7591e+108
  -3.6381e+102
   -1.9676e+96
   -8.4446e+89
   -4.0507e+83
   -2.1474e+77
   -8.1876e+70
   -3.5228e+64
   -1.7350e+58
   -8.8927e+51

Does not happen with ratio = 1e2, but maybe the use case is not so significant...
regards,
Paul Netsaver

Paul Netsaver <netsaver>

 

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    Follow 6 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2021-04-21 mtmiller Summary[octave forge] (signal): decimate function outputs divergent numbers [octave forge] (signal) decimate function outputs divergent numbers
    2021-04-21 mtmiller Item GroupIncorrect Result Inaccurate Result
        Release6.2.0 dev
    2021-04-20 pantxo StatusNone Confirmed
        Operating SystemMicrosoft Windows Any
        Summarydecimate function outputs divergent numbers [octave forge] (signal): decimate function outputs divergent numbers

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