[SciPy-user] special.round(10.5) [was: Installing SciPy on Mac OS X Tiger]
Robert Kern
rkern at ucsd.edu
Wed Jun 8 18:59:54 EDT 2005
Zhiwen Chong wrote:
> I took your advice and checked out a CVS copy and downloaded hpc's g77
> again just now. It builds okay now!
/me does the Happy Build Dance.
> When I ran scipy.test(), it reported "no test file found" for many of
> the modules,
Those are normal. They are reminders to us developers to actually write
those tests.
> but as far as actual failures go, there was only one (out
> of 1174):
>
> FAIL: check_round (scipy.special.basic.test_basic.test_round)
> ----------------------------------------------------------------------
> Traceback (most recent call last):
> File "/Library/Frameworks/Python.framework/Versions/2.4/lib/
> python2.4/site-packages/scipy/special/tests/test_basic.py", line 1789,
> in check_round
> assert_array_equal(rnd,rndrl)
> File "/Library/Frameworks/Python.framework/Versions/2.4/lib/
> python2.4/site-packages/scipy_test/testing.py", line 715, in
> assert_array_equal
> assert cond,\
> AssertionError:
> Arrays are not equal (mismatch 25.0%):
> Array 1: [10 10 10 11]
> Array 2: [10 10 11 11]
>
> I take it that's normal on OS X?
It's an incorrect test, I believe.
Other devs: special.round() has different behavior than scipy.round()
(which is just an alias to Numeric.around()).
In [15]:scipy.round(10.5)
Out[15]:11.0
In [16]:scipy.round(11.5)
Out[16]:12.0
In [17]:scipy.special.round(10.5)
Out[17]:10.0
In [18]:scipy.special.round(11.5)
Out[18]:12.0
I submit that "round-to-nearest-even" is desirable (and in any case
comes part and parcel with using the cephes implementation), and we
should adjust our test case accordingly.
Or rather, I already have.
--
Robert Kern
rkern at ucsd.edu
"In the fields of hell where the grass grows high
Are the graves of dreams allowed to die."
-- Richard Harter
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