bugGNU Octave - Bugs: bug #46247, [octave forge] (control) lsim...

 
 

bug #46247: [octave forge] (control) lsim function - potential numerical problem ; various other edits

Submitter:  Piet Wertelaers <piet>
Submitted:  Mon 19 Oct 2015 09:58:52 AM UTC
   
 
Category:  Octave Package Severity:  3 - Normal
Priority:  5 - Normal Item Group:  None
Status:  Fixed Assigned to:  None
Originator Name:  piet Open/Closed:  * Closed
Release:  * 3.8.2 Operating System:  * GNU/Linux
Fixed Release:  None Planned Release:  None
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Fri 23 Oct 2015 08:41:02 PM UTC, comment #4: 

I've pushed a couple of changesets, the latest result can be seen here:

http://sourceforge.net/p/octave/control/ci/default/tree/inst/lsim.m

Note that it is not possible to use a scalar argument t as tfinal for continuous-time and as tstart for discrete-time models as you proposed. There would be a conflict if the user wants to plot both continuous- and discrete-time models together:


lsim (sys_ct, sys_dt, u, t)


The changes will be part of the upcoming control-3.0.0 which should be ready in late October/early November 2015.
This bug report can be closed.

Lukas Reichlin <paramaniac>
Thu 22 Oct 2015 11:15:26 AM UTC, comment #3: 

Lukas : many lines had been edited, but the scope has stayed limited to the help texinfo (some comments between () to be deleted), and to the function _linear_sumulation_ , and this is why these two portions as loose uploads. But here is the assembled m-file.

(file #35258)

Piet Wertelaers <piet>
Thu 22 Oct 2015 06:12:22 AM UTC, comment #2: 

Piet, may I ask you for a patch created by the diff utility? If that is not possible, just attach your modified lsim.m file as a whole (not portions of it) so I can do the diff for you.

Lukas Reichlin <paramaniac>
Mon 19 Oct 2015 12:39:00 PM UTC, comment #1: 

I am unsure what happened, but the original got lost (probably due to the sensitivity of savannahs markup).

Here is is again (it reads fine in the emails):

> The internal reconstruction of the time vector with  dt = t(2) - t(1);  and  t = reshape (tinitial : dt : tfinal, [], 1);  can be susceptible to round-off, rising unjustified complaints about size inconsistencies between U and T. The attempted fix gives prime importance to the len_t  variable, instead of  dt. On the fly, some other cosmetics are suggested, also in the help text.

Carnë Draug <carandraug>
Group Member
Mon 19 Oct 2015 09:58:52 AM UTC, original submission:  

The internal reconstruction of the time vector with +verbatim+ dt = t(2) - t(1); -verbatim- and +verbatim+ t = reshape (tinitial : dt : tfinal, [], 1); -verbatim- can be susceptible to round-off, rising unjustified complaints about size inconsistencies between U and T. The attempted fix gives prime importance to the +verbatim+ len_t -verbatim- variable, instead of +verbatim+ dt -verbatim- . On the fly, some other cosmetics are suggested, also in the help text.

Piet Wertelaers <piet>

 

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

Attach Files:
   
   
Comment:
   

Attached Files
file #35258:  lsim_modified.m added by piet (11KiB - text/x-objcsrc - Entire m-file upon Lukas' request)
file #35242:  modified_function.txt added by piet (3KiB - text/plain - Corrected a typo abs(max(eig..)) in the function _linear_simulation_)
file #35226:  modified_function.txt added by piet (3KiB - text/plain - Re-worked PORTIONS of the file lsim.m)
file #35227:  modified_header.txt added by piet (4KiB - text/plain - Re-worked PORTIONS of the file lsim.m)

 

Depends on the following items: None found

Items that depend on this one: None found

 

Carbon-Copy List
  • -email is unavailable- added by mtmiller (Updated the item)
  • -email is unavailable- added by jwe (Updated the item)
  • -email is unavailable- added by paramaniac (Posted a comment)
  • -email is unavailable- added by carandraug (Lukas Reichlin - maintainer of the control package)
  • -email is unavailable- added by piet (Submitted the item)
  • -email is unavailable- added by piet (octave control lsim)
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    Follow 9 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2018-05-01 mtmiller StatusNone Fixed
        Open/ClosedOpen Closed
    2017-08-13 jwe Summary[control] lsim() function - potential numerical problem ; various other edits [octave forge] (control) lsim function - potential numerical problem ; various other edits
    2015-10-22 piet Attached File- Added lsim_modified.m, #35258
    2015-10-20 piet Attached File- Added modified_function.txt, #35242
    2015-10-19 carandraug Carbon-Copy- Added -email is unavailable-
    2015-10-19 piet Attached File- Added modified_function.txt, #35226
        Attached File- Added modified_header.txt, #35227
        Carbon-Copy- Added piet

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