[Octave-bug-tracker] [bug #37742] sqp test failure with ATLAS on Debian amd64

[Mike Miller]

URL:
  <http://savannah.gnu.org/bugs/?37742>

                 Summary: sqp test failure with ATLAS on Debian amd64
                 Project: GNU Octave
            Submitted by: mtmiller
            Submitted on: Wed 14 Nov 2012 10:42:16 PM EST
                Category: Libraries
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Incorrect Result
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: dev
        Operating System: GNU/Linux

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Details:

I'm not using sqp, but I have been getting a consistent failure when running
make check, affects both stable and default branches for me. Error is slightly
over the tolerance specified in the test case.

The gotcha is it only fails when libblas.so.3 is configured to point to ATLAS,
and only on Debian 64-bit (testing or unstable). This is the Debian
libatlas3-base package, not a self-compiled ATLAS.

This could conceivably be a bug with the atlas library in Debian, but the
result of the test as shown below is so close and the tolerance of 5*sqrt(eps)
looks arbitrary to me, I think this could be resolved by bumping up the
tolerance here.


$ readlink -f /usr/lib/libblas.so.3
/usr/lib/atlas-base/atlas/libblas.so.3.0
$ ./run-octave -qf --eval="test sqp"
  ***** test

 x0 = [-1.8; 1.7; 1.9; -0.8; -0.8];

 [x, obj, info, iter, nf, lambda] = sqp (x0, @__phi, @__g, []);

 x_opt = [-1.717143501952599;
           1.595709610928535;
           1.827245880097156;
          -0.763643103133572;
          -0.763643068453300];

 obj_opt = 0.0539498477702739;

 assert (x, x_opt, 5*sqrt (eps));
 assert (obj, obj_opt, sqrt (eps));
!!!!! test failed
assert (x,x_opt,5 * sqrt (eps)) expected
  -1.71714
   1.59571
   1.82725
  -0.76364
  -0.76364
but got
  -1.71714
   1.59571
   1.82725
  -0.76364
  -0.76364
maximum absolute error 9.34422e-08 exceeds tolerance 7.45058e-08





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