On Thu, Sep 18, 2014 at 10:56 AM, Tab Atkins Jr. <[email protected]> wrote:
> On Thu, Sep 18, 2014 at 3:17 AM, Claude Pache <[email protected]> > wrote: > > Question: Should Math.log2 give exact results for powers of 2? > > > > The same issue holds for Math.log10 (might be applicable for nonnegative > > powers only): Math.log10(1e15) != 15 in Chrome. > > I have no idea of the computation complexity underlying a log > implementation, so given that: yes, it should totally give exact > results for powers of 2, and log10 should do the same for (positive) > powers of 10. (Negative powers of 10 can't actually be represented by > a JS number, so there's no need to talk about them.) It would also be useful, though perhaps not feasible, if they are guaranteed to be monotonic everywhere and strictly monotonic near those exact values; that is, for all x < 2^k, log2(x) < k for all x > 2^k, log2(x) > k and similarly for log10. If this property held, then naïve "number of digits" tests expressed using logarithms would always give the right answers. (This probably conflicts with generally desirable rounding properties, however.)
_______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
