LOG10E mystery constant

Gavin Barraclough barraclough at apple.com
Mon Feb 21 13:16:56 PST 2011


Hi Mark,

I've fixed this value for Safari in WebKit r79246.

cheers,
G.

On Feb 20, 2011, at 10:04 PM, Mark S. Miller wrote:

> That's what I needed. Thanks.
> 
> On Sun, Feb 20, 2011 at 9:53 PM, Rico Wind <ricow at google.com> wrote:
> This was recently fixed in V8, see:
> http://code.google.com/p/chromium/issues/detail?id=72555
> 
> Cheers,
> Rico
> 
> On Feb 21, 2011 6:47 AM, "Mark S. Miller" <erights at google.com> wrote:
> > On Sun, Feb 20, 2011 at 9:26 PM, John Cowan <cowan at mercury.ccil.org> wrote:
> > 
> >> Mark S. Miller scripsit:
> >>
> >> > This is the only constant whose actual value differs across browsers:
> >> >
> >> > 0.43429448190325176 v8 version 2.3.9 [console: dumb]
> >> > 0.4342944819032518 Chrome 11.0.672.2 dev
> >>
> >> [etc.]
> >>
> >> The two values are really the same value when represented as an IEEE
> >> double. The difference is in the printing routine, not the internal
> >> representation. Specifically, the "...2518" browsers are rounding, the
> >> "...25176" browsers are not.
> >>
> > 
> > But they convert to back to two different floating point numbers, at least
> > on all the browsers I quickly tried.
> > 
> >> 0.43429448190325176 === 0.4342944819032518
> > false
> >> 0.43429448190325176 < 0.4342944819032518
> > true
> >> 0.43429448190325176 > 0.4342944819032518
> > false
> > 
> > A little more testing reveals that the two numbers seem to be consecutive,
> > in the sense that there are no intermediate representable numbers.
> > 
> > 
> >>
> >> "Floating-point numbers are a little like sandpiles; every time you pick
> >> one up, you get a little less sand and a little more dirt." (But this
> >> is not true of integers up to 2^53, slightly less than 10^16.
> >>
> >> --
> >> John Cowan <cowan at ccil.org>
> >> Yakka foob mog. Grug pubbawup zink wattoom gazork. Chumble spuzz.
> >> --Calvin, giving Newton's First Law "in his own words"
> >>
> > 
> > 
> > 
> > -- 
> > Cheers,
> > --MarkM
> 
> 
> 
> -- 
>     Cheers,
>     --MarkM
> _______________________________________________
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> es-discuss at mozilla.org
> https://mail.mozilla.org/listinfo/es-discuss

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