A bug with Sum (as in Monoid)

[Dannyu NDos]

Imprecise calculation shouldn't be considered as a bug. Topologically
speaking, floating point types are regarded as if they had countably
infinite precision. So the elements in domain are positive reals, negative
reals, the zeros, the infinities, and the NaN.

2019년 11월 7일 (목) 07:29, Brent Yorgey <byorgey at gmail.com>님이 작성:

> Hint: the problem has nothing to do with zeros.
>
> λ> 0.1 + (0.2 + 0.3) == (0.1 + 0.2) + 0.3
> False
>
>
> On Wed, Nov 6, 2019 at 4:20 PM Dannyu NDos <ndospark320 at gmail.com> wrote:
>
>> Omg, addition is not even associative? The zeros truly ruined everything.
>>
>> 2019년 11월 7일 (목) 06:58, Brent Yorgey <byorgey at gmail.com>님이 작성:
>>
>>> How is that worse than the fact that addition is already not associative
>>> for floating point types?  At least +0 is really the identity up to (==).
>>>
>>> On Wed, Nov 6, 2019, 3:49 PM Dannyu NDos <ndospark320 at gmail.com> wrote:
>>>
>>>> Sum has bug with floating points. Current definition states +0 as the
>>>> identity element, while the actual identity is -0 since +0 + -0 = +0.
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