[Python-ideas] statistics module in Python3.4

[Steven D'Aprano]

On Fri, Jan 31, 2014 at 02:56:39PM +0900, Stephen J. Turnbull wrote:
> Steven D'Aprano writes:
> 
>  > Floats violate several of the fundamental rules of mathematics,
>  > e.g. addition is not commutative:
> 
> AFAIK it is.
> 
>  > py> 1e19 + (-1e19 + 0.1) == (1e19 + -1e19) + 0.1
>  > False
> 
> This is a failure of associativity, not commutativity.

Oops, you are correct. I got them mixed up.

http://en.wikipedia.org/wiki/Associativity

However, commutativity of addition can violated by Python numeric types, 
although not floats alone. E.g. the example I gave earlier of two int 
subclasses.



-- 
Steven