On 08/31/2017 01:53 AM, Pavol Lisy wrote:
On 8/31/17, Terry Reedy <tjre...@udel.edu> wrote:
On 8/30/2017 1:35 PM, Terry Reedy wrote:
https://stackoverflow.com/questions/45965545/math-sqrt-domain-error-when-square-rooting-a-positive-number
reports the following:
-----
Microsoft Windows [Version 10.0.16251.1002]
(c) 2017 Microsoft Corporation. All rights reserved.
C:\Users\Adam>python
Python 3.6.2 (v3.6.2:5fd33b5, Jul 8 2017, 04:14:34) [MSC v.1900 32 bit
(Intel)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import math
>>> math.sqrt(1.3)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ValueError: math domain error
>>>
I upgraded from version 3.6.1 to 3.6.2 to try to resolve the issue and
restarted my computer but it is still occurring. Some numbers are
working (1.2, 1.4) and some others are also not working (1.128).
----
Neither installed 64 bit 3.6.2 nor my repository 3.6 32-bit debug build
reproduce this. If anyone has the python.org 32bit 3.6.1/2 releases
installed on Windows, please test and report.
Three people have reported that math.sqrt(1.3) works in 32 bit Python on
64-bit Windows and no one otherwise. I reported back on SO that the
problem is likely local. Thanks for the responses.
Problem is reported on win10 and I see just 2 tests on win7 (third is
maybe Terry's but on SO I don't see win version).
If I am not wrong (with analyze source code) sqrt is calling function
from "libm" which is some kind of msvcrt.dll on windows... (see
https://github.com/python/cpython/blob/a0ce375e10b50f7606cb86b072fed7d8cd574fe7/Modules/mathmodule.c#L1183
and
https://github.com/python/cpython/blob/6f0eb93183519024cb360162bdd81b9faec97ba6/Lib/ctypes/util.py#L34
)
And with "MSC v. 1900 ..." it seems that "alternative approaches"
(see here https://bugs.python.org/issue23606 ) are used.
So I would be cautious.
PS.
BTW on my ubuntu I got this:
from ctypes import cdll
print(cdll.LoadLibrary("libcrypt.so"))
<CDLL 'libcrypt.so', handle 21d0860 at 0x7fcce2f22f28>
print(cdll.LoadLibrary("libm.so"))
...
OSError: /usr/lib/x86_64-linux-gnu/libm.so: invalid ELF header
(same with distro's python3, python2 and anaconda 3.6.2)
So this test ->
https://github.com/python/cpython/blob/6f0eb93183519024cb360162bdd81b9faec97ba6/Lib/ctypes/util.py#L328
has to crash on some environments (see for example:
https://github.com/scipy/scipy/pull/5416/files ). And it seems like
some test failures are just ignored...
Valid point, fired up a windows 10 machine and worked as well.
Python 3.6.2 (v3.6.2:5fd33b5, Jul 8 2017, 04:14:34) [MSC v.1900 32 bit
(Intel)] on win32
Type "copyright", "credits" or "license()" for more information.
>>> import math
>>> math.sqrt(1.3)
1.140175425099138
>>>
This machine does not have the creators update yet. So there's that.
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