modulo

raul mihaila raul.mihaila at gmail.com
Mon Sep 16 08:58:12 PDT 2013


Thanks Claude, I was missing something, it's clear now.


On Mon, Sep 16, 2013 at 4:27 PM, Claude Pache <claude.pache at gmail.com>wrote:

>
> Le 16 sept. 2013 à 15:12, raul mihaila <raul.mihaila at gmail.com> a écrit :
>
> But if the definition of modulo is correct, then isn't ToInt32 wrong?
> http://people.mozilla.org/~jorendorff/es6-draft.html#sec-7.1.5
> Here, -3 is transformed into 3.
>
>
> If one follows carefully the algorithm, one has:
> * step 4: `int == -3`;
> * step 5: `int32bit == 2^32 - 3`;
> * step 6 (since `int32bit` ≥ 2^31`): return `int32bit - 2^32 == -3`.
> (Note that at no step there is a direct sign change like `-3` into `3` or
> vice versa; but the value shifts by multiples of `2^32` in order to go into
> the right interval.)
>
> —Claude
>
>
> Raul M
>
>
> On Mon, Sep 16, 2013 at 2:40 PM, Claude Pache <claude.pache at gmail.com>wrote:
>
>>
>> Le 16 sept. 2013 à 11:30, raul mihaila <raul.mihaila at gmail.com> a écrit :
>>
>> Hello,
>>
>> I think the definition of modulo is wrong.
>> http://people.mozilla.org/~jorendorff/es6-draft.html#sec-5.2
>> k should be of the same sign as x not as y.
>>
>>
>> I think the definition is correct, and is more useful than the opposite
>> convention. It is indeed the opposite convention of the one used by the
>> remainder operator (`%` in JS), but it is not the remainder operator. (BTW,
>> is there any chance that the modulo operator [1] will be introduced in
>> EcmaScript, rather sooner than later?)
>>
>> [1] http://wiki.ecmascript.org/doku.php?id=strawman:modulo_operator
>>
>> In fact, since `x modulo y` is apparently only use with positive (and
>> integral) `y` in the specification, the definition should be simplified, by
>> restricting to the case where `y` is positive.
>>
>>
>> Also, shouldn't ToUint32 and ToUint16 return only positive numbers? If
>> the argument is, for example, -3, the result will be -3 (assuming that the
>> modulo definition is wrong). Or maybe the argument will never be negative?
>>
>>
>> Assuming the modulo definition is correct, `ToUint32` and `ToUint16` work
>> as expected (if the argument is `-3` the result is `2^32-3`, resp. `2^16-3`.
>>
>> —Claude
>>
>>
>>
>> Raul M
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>> es-discuss at mozilla.org
>> https://mail.mozilla.org/listinfo/es-discuss
>>
>>
>>
>>
>
>
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