on floating-point numbers

[Christian Gollwitzer]

Am 02.09.21 um 21:02 schrieb Julio Di Egidio:
> On Thursday, 2 September 2021 at 20:43:36 UTC+2, Chris Angelico wrote:
>> On Fri, Sep 3, 2021 at 4:29 AM Hope Rouselle <hrou... at jevedi.com> wrote:
> 
>>> All I did was to take the first number, 7.23, and move it to the last
>>> position in the list. (So we have a violation of the commutativity of
>>> addition.)
>>>
>> It's not about the commutativity of any particular pair of operands -
>> that's always guaranteed.
> 
> Nope, that is rather *not* guaranteed, as I have quite explained up thread.
> 

No, you haven't explained that. You linked to the famous Goldberg paper. 
Where in the paper does it say that operations on floats are not 
commutative?

I'd be surprised because it is generally wrong.
Unless you have special numbers like NaN or signed zeros etc., a+b=b+a 
and a*b=b*a holds also for floats.

	Christiah