bugGNU Octave - Bugs: bug #48905, [octave forge] (lssa) lscomplex...

 
 

bug #48905: [octave forge] (lssa) lscomplex and fastlscomplex behave differently

Submitted by:  Rafael Laboissiere <rlaboiss>
Submitted on:  Thu 25 Aug 2016 07:55:40 PM UTC  
 
Category:  Octave Forge Package Severity:  3 - Normal
Priority:  5 - Normal Item Group:  Incorrect Result
Status:  None Assigned to:  None
Originator Name:  Open/Closed:  Open
Release:  other Operating System:  GNU/Linux

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Mon 23 Jul 2018 04:49:39 PM UTC, comment #1: 

According to the doc, it is the same functionality, however fastlscomplex least squares from a divide and conquer algorithm

having said that, since the numbers are very different, one of the functions is probally incorrect but needs someone with more understanding of the functions to fix it.

John Donoghue <lostbard>
Project Member
Thu 25 Aug 2016 07:55:40 PM UTC, original submission:  

If I understand correctly, lscomplex and fastlscomplex implement the same functionality, but in Octave or in C++ language, respectively.  If this is true, then they should yield identical results for the same arguments.  Now, this does not seem to be the case in version 0.1.2 of the lssa package:

octave:1> pkg load lssa
octave:2> maxfreq = 4 / ( 2 * pi );
octave:3> t = [0:0.008:8];
octave:4> x = (2 .* sin (maxfreq .* t) +
      3 .* sin ((3 / 4) * maxfreq .* t) -
      0.5 .* sin ((1/4) * maxfreq .* t) -
      0.2 .* cos (maxfreq .* t) +
      cos ((1/4) * maxfreq .* t));
octave:5> lscomplex (t, x, maxfreq, 2, 2)
ans =

  -0.40092 - 2.37156i   1.21807 - 2.25613i   1.93543 - 1.53949i   2.13669 - 0.98053i

octave:6> fastlscomplex (t, x, maxfreq, 2, 2)
ans =

  -0.4009 - 2.3716i   1.2181 - 2.2561i   0.1751 - 2.3014i   1.0019 - 2.0248i

Rafael Laboissiere <rlaboiss>

 

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    Follows 1 latest change.

    Date Changed by Updated Field Previous Value => Replaced by
    2017-08-13 jwe Summarylssa: lscomplex and fastlscomplex behave differently => [octave forge] (lssa) lscomplex and fastlscomplex behave differently

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