[Octave-bug-tracker] [bug #53242] tests: 'test subspace.m' fails randomly

[Mike Miller]

URL:
  <http://savannah.gnu.org/bugs/?53242>

                 Summary: tests: 'test subspace.m' fails randomly
                 Project: GNU Octave
            Submitted by: mtmiller
            Submitted on: Tue 27 Feb 2018 05:08:32 PM PST
                Category: Test Suite
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Inaccurate Result
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: dev
        Operating System: GNU/Linux

    _______________________________________________________

Details:

The test of subspace with norm and acos fails relies on random data and fails
randomly with a tolerance error some small percentage of the time. For
example


***** test
 ## For random vectors
 a = rand (2,1);
 b = rand (2,1);
 a1 = norm (a,2);
 b1 = norm (b,2);
 theta = acos (dot (a,b)/(a1*b1));
 assert (theta, subspace (a, b), 100*eps);
!!!!! test failed
ASSERT errors for:  assert (theta,subspace (a, b),100 * eps)

  Location  |  Observed  |  Expected  |  Reason
     ()       0.0027191    0.0027191     Abs err 7.2089e-14 exceeds tol
2.2204e-14 by 5e-14


7.2089e-14 is the largest absolute error I've seen so far in testing this
several hundred times, which is about 325*eps.

Any better guesses on a good upper bound on the tolerance?

Or do we want to seed the random generator to a fixed state like we have done
for other unit tests?




    _______________________________________________________

Reply to this item at:

  <http://savannah.gnu.org/bugs/?53242>

_______________________________________________
  Message sent via/by Savannah
  http://savannah.gnu.org/