On Thu, Jan 16, 2014 at 12:09 PM, Joshua Bell <[email protected]> wrote:
> > > > On Thu, Jan 16, 2014 at 10:07 AM, Mark S. Miller <[email protected]>wrote: > >> On Thu, Jan 16, 2014 at 8:40 AM, Jason Orendorff < >> [email protected]> wrote: >> >>> At the risk of putting too many nails in the board... >>> >>> The rationale seems to propose that (0).clz() === 32, but the >>> hypothetical uint64(0).clz() would return 64. That seems like a bad >>> idea though. It's weird for two zero values to get such different >>> behavior from the same method. It's weird for floating-point numbers >>> to have a clz() method in the first place. >>> >>> Since these are two different mathematical functions, they should have >>> different names: Math.clz32(zero) would be 32 no matter what type of >>> zero you pass it; the hypothetical Math.clz64(zero) would of course be >>> 64. That way users can focus on the mathematical function being >>> computed, rather than runtime types. >>> >>> Or maybe: flip the function around so that it returns the number of >>> bits in the binary expansion of the value: Math.bitlen(15) === 4. This >>> is just (32 - CLZ), so it effectively computes the same thing as clz. >>> The advantage is that it extends naturally to integers of any size. >>> >> >> +1. I like this flipping idea by far the best. It can be explained in >> terms of the number being denoted, without referring to the internal >> limitations of any particular representation. With this change, I agree it >> should be a static on Math. >> >> With this flipped idea, let's think through what the proper .bitlen >> answers are for fractions, negative numbers, NaN, +/- Infinity, and -0.0. >> > > Would Math.bitlen(Number.MAX_SAFE_INTEGER) return 53 or 32? > Since the point is to make the answer have a mathematical relationship to the number denoted, rather than the limits of a particular representation, 53. > > (If 53, environments trying to emulate 32-bit ints on top of Number could > toss in yet another |0 or >>>0) > yes. -- Cheers, --MarkM
_______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
