On 13/07/2013, at 01:24, Jeff Walden wrote:
> On 07/12/2013 04:13 PM, Tab Atkins Jr. wrote:
>> If you don't agree with that reasoning, then I suppose you'd argue
>> that *all* numbers > 2^53 should return true, since they're all forced
>> into being represented as integers?
>
> All numbers >= 2**53 except Infinity, yes. I think "isInteger" implies the
> mathematical concept, with the only addition that it should pass -0. And
> while it would somewhat unfortunately diverge from the ToInteger spec
> operation, "toInteger" should imply the mathematical concept as well, and
> only produce values that are mathematical integers. ("toInteger" should
> probably convert -0 to -0 for consistency with "isInteger" on -0, but
> probably I could go either way here.)
Everything from Math.pow(2,52) to Math.pow(2,53) are integers (if represented
as IEE-754 doubles), because there's no bit left to represent Math.pow(2,-1):
Math.pow(2,52)
4503599627370496
Math.pow(2,52).toString(2)
"10000000000000000000000000000000000000000000000000000"
Math.pow(2,52).toString(2).length
53
(Math.pow(2,52)-1).toString(2)
"1111111111111111111111111111111111111111111111111111"
(Math.pow(2,52)-1).toString(2).length
52
Math.pow(2,52)-0.5
4503599627370495.5
Math.pow(2,52)+0.5
4503599627370496
--
( Jorge )();
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