On Fri, Apr 17, 2009 at 3:58 PM, Scott David Daniels
wrote:
> Non-associativity is what makes for floating point headaches.
> To my knowledge, floating point is at least commutative.
Well, mostly. :-)
>>> from decimal import Decimal
>>> x, y = Decimal('NaN123'), Decimal('-NaN456')
>>> x + y
Deci
Greg Ewing wrote:
Steven D'Aprano wrote:
it should be obvious in the same way that string concatenation is
different from numerical addition:
1 + 2 = 2 + 1
'1' + '2' != '2' + '1'
However, the proposed arithmetic isn't just non-
commutative, it's non-associative, which is a
much rarer and mor
Steven D'Aprano wrote:
it should be obvious in the
same way that string concatenation is different from numerical
addition:
1 + 2 = 2 + 1
'1' + '2' != '2' + '1'
However, the proposed arithmetic isn't just non-
commutative, it's non-associative, which is a
much rarer and more surprising thing
On Fri, 17 Apr 2009 12:10:59 pm Tennessee Leeuwenburg wrote:
> Actually, that's a point.
>
> If its' the 31st of Jan, then +1 monthdelta will be 28 Feb and
> another +1 will be 28 March whereas 31st Jan +2 monthdeltas will be
> 31 March.
>
> That's the kind of thing which really needs to be documen
Tennessee> If its' the 31st of Jan, then +1 monthdelta will be 28 Feb
Tennessee> and another +1 will be 28 March whereas 31st Jan +2
Tennessee> monthdeltas will be 31 March.
Other possible arithmetics:
* 31 Jan 2008 + monthdelta(2) might be
31 Jan 2008 + 31 days (# days i
Actually, that's a point.
If its' the 31st of Jan, then +1 monthdelta will be 28 Feb and another +1
will be 28 March whereas 31st Jan +2 monthdeltas will be 31 March.
That's the kind of thing which really needs to be documented, or I think
people really will make mistakes.
For example, should a
Jess Austin wrote:
This is a perceptive observation: in the absence of parentheses to
dictate a different order of operations, the third quantity will
differ from the second.
Another aspect of this is the use case mentioned right
at the beginning of this discussion concerning a recurring
event
Jared Grubb wrote:
> On 16 Apr 2009, at 11:42, Paul Moore wrote:
>> The key thing missing (I believe) from dateutil is any equivalent of
>> monthmod.
>
>
> I agree with that. It's well-defined and it makes a lot of sense. +1
>
> But, I dont think monthdelta can be made to work... what should the
>
