If you are running 32-bit 3.6 on Windows, please test this

[20/20 Lab]

On 08/31/2017 01:53 AM, Pavol Lisy wrote:
> On 8/31/17, Terry Reedy <tjreedy at 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.