bugGNU Octave - Bugs: bug #40057, exit criterion in pcg


bug #40057: exit criterion in pcg

Submitted by:  Marco Caliari <caliari>
Submitted on:  Wed 18 Sep 2013 09:40:46 AM UTC  
Category: Octave FunctionSeverity: 2 - Minor
Priority: 5 - NormalItem Group: Matlab Compatibility
Status: FixedAssigned to: None
Originator Name: Open/Closed: Closed
Release: 3.6.2Operating System: GNU/Linux

Add a New Comment(Rich Markup)

You are not logged in

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


Thu 17 Oct 2013 11:05:42 PM UTC, comment #1:

I changed the criterion in this changeset (http://hg.savannah.gnu.org/hgweb/octave/rev/f6fded839513). Closing report.

Rik <rik5>
Project Administrator
Wed 18 Sep 2013 09:40:46 AM UTC, original submission:

Dear all,

the exit criterion in pcg is

On the other hand, in C.T. Kelley (quoted as reference book), p.23, it is used

and the same in matlab (as I understand from the description of [X,FLAG,RELRES] output). Of course, Octave criterion is a valid one and they coincide for X0 = zeros (the default value). I think it should be changed for compatibility. If one really needs the current behavior, he can give TOL * norm (B - A * X0) / norm (B) as input tolerance.



Marco Caliari <caliari>
Project Member


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

Attach File(s):

No files currently attached


Depends on the following items: None found

Items that depend on this one: None found


Carbon-Copy List
  • -unavailable- added by rik5 (Posted a comment)
  • -unavailable- added by caliari (Submitted the item)

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

    Only project members can vote.


    Please enter the title of George Orwell's famous dystopian book (it's a date):



    Follow 2 latest changes.

    Date Changed By Updated Field Previous Value => Replaced By
    Thu 17 Oct 2013 11:05:42 PM UTCrik5StatusNone=>Fixed

    Back to the top

    Powered by Savane 3.1-cleanup1