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

Add a New Comment (Rich Markup)

You are not logged in

Please log in, so followups can be emailed to you.


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>


(Note: upload size limit is set to 16384 kB, after insertion of the required escape characters.)

Attach Files:

No files currently attached


Depends on the following items: None found

Items that depend on this one: None found


Carbon-Copy List
  • -email is unavailable- added by lostbard (Posted a comment)
  • -email is unavailable- added by jwe (Updated the item)
  • -email is unavailable- added by rlaboiss (Submitted the item)

    Do you think this task is very important?
    If so, you can add your encouragement to it.
    This task has 0 encouragements so far.

    Only project members can vote.




    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

    Back to the top

    Powered by Savane 3.5