[SciPy-dev] test error on Solaris using Sun's compilers

[Skip Montanaro]

I installed SciPy on a Solaris machine using Sun's C and Fortran compilers
(hint for the unwary: this was *not* a straightforward exercise).  During
the test run I got a single failure (this is reproducible, not an anomaly
due to different random inputs):

    FAIL: check_basic (test_morestats.test_shapiro)
    ----------------------------------------------------------------------
    Traceback (most recent call last):
      File "/home/skip/local/SunOS/lib/python2.2/site-packages/scipy/stats/tests/test_morestats.py", line 30, in check_basic
        assert_almost_equal(w,0.90047299861907959,8)
      File "/home/skip/local/SunOS/lib/python2.2/site-packages/scipy_base/testing.py", line 283, in assert_almost_equal
        assert round(abs(desired - actual),decimal) == 0, msg
    AssertionError: 
    Items are not equal:
    DESIRED: 0.900472998619
    ACTUAL: 0.900472760201

After a little bit of debugging, I concluded the problem is most likely in
the Fortran code.  Using the first input list in the test:

    x1 = [0.11,7.87,4.61,10.14,7.95,3.14,0.46,
          4.43,0.21,4.75,0.71,1.52,3.24,
          0.93,0.42,4.97,9.53,4.55,0.47,6.66]

I manually executed the code in scipy.stats.morestats.shapiro, and got
different results from the statlib.swilk call.  On the Sun I got:

    >>> scipy.stats.statlib.swilk(y,a[:N/2],init)
    (array([ 0.47337097,  0.32174039,  0.25566325,  0.20829722,  0.16863985,  0.13358422,
                 0.10147439,  0.07128929,  0.04232321,  0.01403512],'f'), 0.90047276020050049, 0.042089268565177917, 0)

On Linux I got:

    >>> scipy.stats.statlib.swilk(y,a[:N/2],init)
    (array([ 0.47337109,  0.32174024,  0.25566328,  0.20829724,  0.16863985,  0.13358422,
                 0.1014744 ,  0.0712893 ,  0.04232322,  0.01403512],'f'), 0.90047299861907959, 0.042089745402336121, 0)

I can try compiling the underlying Fortran file with different flags (no
optimization for instance).  What else could/should I try?

Thanks,

-- 
Skip Montanaro
skip at pobox.com
consulting: http://manatee.mojam.com/~skip/resume.html