[Octave-bug-tracker] [bug #49470] [MXE] eig.cc-tst failure in __run_test_suite__.m with 64-bit-Octave

[Markus Mützel]

Follow-up Comment #16, bug #49470 (project octave):

After reading Barbara's blog [1], I conclude that the test was intended to
check whether the correct default decomposition method is used for symmetric
input.
The failing test on Octave for Windows 64bit basically comes down to the
following equality failing there (see also Avinoam's comment #7):

>> isequal(1e-15, 10^-15)
ans = 0


In the attached patch, I changed the failing test to use numeric literals
instead of the power. With that change it produces the same results for "chol"
and "qz" on Windows 64bit and Linux. I also added a comment that clarifies
what is checked, and merged the three similar tests into one.

I also tried to find a non-symmetric matrix that produces different results
for "chol" and "qz" but was unsuccessful to find one. Maybe someone that is
more familiar with the algorithms/numerics involved can add a test for this
case, too.

[1]:
http://barbaralocsigsoc2016.blogspot.de/2016/07/cholqz-and-matrixvector-flags.html

(file #41503)
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Additional Item Attachment:

File name: bug49470_eig_test.patch        Size:1 KB


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