[Numpy-discussion] Test error with ATLAS, Windows 64 bit

[Julian Taylor]

The official numpy mingw binaries do not have all these math issues.
Only the VC builds do.
As mingw is fine the functions must be somewhere in the windows API but
no-one has contributed a fix for the VC builds to numpy yet.

On 14.04.2014 22:43, Carl Kleffner wrote:
> Hi,
> 
> mingw has expm1. Is this function suitable?
> 
> Regards
> 
> Carl
> 
> 
> 
> 
> 2014-04-14 21:34 GMT+02:00 Eric Moore <ewm at redtetrahedron.org
> <mailto:ewm at redtetrahedron.org>>:
> 
> 
> 
>     On Monday, April 14, 2014, Matthew Brett <matthew.brett at gmail.com
>     <mailto:matthew.brett at gmail.com>> wrote:
> 
>         Hi,
> 
>         On Mon, Apr 14, 2014 at 12:12 PM, Warren Weckesser
>         <warren.weckesser at gmail.com> wrote:
>         >
>         > On Mon, Apr 14, 2014 at 2:59 PM, Matthew Brett
>         <matthew.brett at gmail.com>
>         > wrote:
>         >>
>         >> Hi,
>         >>
>         >> With Carl Kleffner, I am trying to build a numpy 1.8.1 wheel for
>         >> Windows 64-bit, and latest stable ATLAS.
>         >>
>         >> It works fine, apart from the following test failure:
>         >>
>         >>
>         ======================================================================
>         >> FAIL: test_special (test_umath.TestExpm1)
>         >>
>         ----------------------------------------------------------------------
>         >> Traceback (most recent call last):
>         >>   File
>         "C:\Python27\lib\site-packages\numpy\core\tests\test_umath.py",
>         >> line 329, in test_special
>         >>     assert_equal(ncu.expm1(-0.), -0.)
>         >>   File
>         "C:\Python27\lib\site-packages\numpy\testing\utils.py", line
>         >> 311, in assert_equal
>         >>     raise AssertionError(msg)
>         >> AssertionError:
>         >> Items are not equal:
>         >>  ACTUAL: 0.0
>         >>  DESIRED: -0.0
>         >>
>         >> Has anyone seen this?  Is it in fact necessary that
>         expm1(-0.) return
>         >> -0 instead of 0?
>         >>
>         >
>         >
>         > What a cowinky dink.  This moring I ran into this issue in a
>         scipy pull
>         > request (https://github.com/scipy/scipy/pull/3547), and I
>         asked about this
>         > comparison failing on the mailing list a few hours ago.  In
>         the pull
>         > request, the modified function returns -0.0 where it used to
>         return 0.0, and
>         > the test for the value 0.0 failed.  My work-around was to use
>         > `assert_array_equal` instead of `assert_equal`.  The array
>         comparison
>         > functions treat the values -0.0 and 0.0 as equal.
>          `assert_equal` has code
>         > that checks for signed zeros, and fails if they are not the
>         same sign.
> 
>         Yes, sorry, I should have mentioned that I saw your post too.  I'd
>         live to use that workaround, but it looks like the teste against
>         -0 is
>         intentional, and I was hoping for help understanding.
> 
>         The relevant two lines of the test are:
> 
>                 assert_equal(ncu.expm1(0.), 0.)
>                 assert_equal(ncu.expm1(-0.), -0.)
> 
>         Julian - I think this one is for you - as the author of these lines:
> 
>         f53ab41a numpy/core/tests/test_umath.py     (Julian Taylor
>         2014-03-02 02:55:30 +0100  329)         assert_equal(ncu.expm1(-0.),
>         -0.)
> 
>         Can you say why you wanted -0 specifically?  Any clue as to why
>         ATLAS
>         64 bit may give 0 instead?
> 
>         Cheers,
> 
>         Matthew
>         _______________________________________________
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> 
> 
>     I think this is a real bug in the version of exp1m in
>     core/src/npymath/npy_math.c.src that's being used since your windows
>     build couldn't find a system version of exp1m to use. 
> 
>     Eric
> 
>      
> 
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> 
> 
> 
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