bugGNU Octave - Bugs: bug #53319, tests: 'test tfqmr.m' fails about...

 
 

bug #53319: tests: 'test tfqmr.m' fails about 5% of the time

Submitter:  Mike Miller <mtmiller>
Submitted:  Sun 11 Mar 2018 01:01:51 AM UTC
   
 
Category:  Test Suite Severity:  3 - Normal
Priority:  5 - Normal Item Group:  Inaccurate Result
Status:  Fixed Assigned to:  None
Originator Name:  Open/Closed:  * Closed
Release:  * dev Operating System:  * GNU/Linux
Fixed Release:  None Planned Release:  None
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Wed 21 Mar 2018 08:18:49 PM UTC, comment #3: 

@Marco: I pushed your cset here: http://hg.savannah.gnu.org/hgweb/octave/rev/27d68d7a482c.

I ran the tests for tfqmr in a loop 1,000 times and saw no failures after this cset.

Rik <rik5>
Group administrator
Fri 16 Mar 2018 03:19:14 PM UTC, comment #2: 

It is not clear to me what was the purpose of such a test. In the attached patch I removed the randomness and tested the Jacobi preconditioner.

(file #43571)

Marco Caliari <caliari>
Group Member
Sun 11 Mar 2018 01:09:01 AM UTC, comment #1: 

this is likely the same issue as bug #53258

the test is checking the error but the actual
convergence check is probably on the residual.

cristiano, can you confirm this?


Carlo de Falco <cdf>
Group Member
Sun 11 Mar 2018 01:01:51 AM UTC, original submission:  

Test #4 in the newly added function file tfqmr.m fails on its random input about 5% of the time (about 4-6 times out of 100).

Example:


***** test
 n = 10;
 tol = 1e-8;
 a = (2 * sprand (n, n, .1) - 1) + 1i * (2 * sprand (n, n, .1) - 1);
 A = a + 2 * eye (n);
 b = sum (A, 2);
 [x, flag, relres, iter, resvec] = tfqmr (A, b, tol, [], diag (diag (A)));
 assert (x, ones (size (b)), 1e-7);
!!!!! test failed
ASSERT errors for:  assert (x,ones (size (b)),1e-7)

  Location  |  Observed  |  Expected  |  Reason
    (1)      1-2.1148e-08i      1         Abs err 1.154e-07 exceeds tol 1e-07 by 2e-08
    (10)     1+5.4148e-08i      1         Abs err 1.101e-07 exceeds tol 1e-07 by 1e-08


The largest absolute error I have seen so far is 1.6043e-07 out of a few thousand trials.

Cc: cdf, cristianodorigo

Mike Miller <mtmiller>
Group Member

 

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Attached Files
file #43571:  tfqmr.diff added by caliari (1KiB - application/x-tex)

 

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    Follow 7 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2018-03-21 rik5 StatusPatch Submitted Fixed
        Open/ClosedOpen Closed
    2018-03-16 caliari Attached File- Added tfqmr.diff, #43571
        StatusNone Patch Submitted
    2018-03-11 cdf Dependencies- Depends on bugs #53258
    2018-03-11 mtmiller Carbon-Copy- Added cdf
        Carbon-Copy- Added cristianodorigo

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