Unexpected behaviour of math.floor, round and int functions (rounding)

[ast]

Le 19/11/2021 à 03:51, MRAB a écrit :
> On 2021-11-19 02:40, 2QdxY4RzWzUUiLuE at potatochowder.com wrote:
>> On 2021-11-18 at 23:16:32 -0300,
>> René Silva Valdés <rene.silva.valdes at gmail.com> wrote:
>>
>>> Hello, I would like to report the following issue:
>>>
>>> Working with floats i noticed that:
>>>
>>> int(23.99999999999999/12) returns 1, and
>>> int(23.999999999999999/12) returns 2
>>>
>>> This implies that int() function is rounding ...
>>
>> It's not int() that's doing the rounding; that second numerator is being
>> rounded before being divided by 12:
>>
>>      Python 3.9.7 (default, Oct 10 2021, 15:13:22)
>>      [GCC 11.1.0] on linux
>>      Type "help", "copyright", "credits" or "license" for more 
>> information.
>>      >>> 23.999999999999999
>>      24.0
>>      >>> (23.999999999999999).hex()
>>      '0x1.8000000000000p+4'
>>
> I think this is a bit clearer because it shows that it's not just being 
> rounded for display:
> 
> Python 3.10.0 (tags/v3.10.0:b494f59, Oct  4 2021, 19:00:18) [MSC v.1929 
> 64 bit (AMD64)] on win32
> Type "help", "copyright", "credits" or "license" for more information.
>  >>> 23.99999999999999 == 24
> False
>  >>> 23.999999999999999 == 24
> True

 >>> 0.3 + 0.3 + 0.3 == 0.9
False