Re: better float2str() C code, anyone?

[David Jones <drj@...>]

On Dec 01, 2004, at 21:37, Asko Kauppi wrote:

> Hmm.. could the behaviour be checked at runtime, and altered?

Not easily no.

Though one could check a few commonly bad cases.  I see an opportunity 
for the autoconf crowd.

Cheers,
 drj
> 1.12.2004 kello 23:25, David Jones kirjoitti:
>
>
> > On Dec 01, 2004, at 14:54, Luiz Henrique de Figueiredo wrote:
> >
> > > > One issue I've had from time to time is that the default
> > > >    #define LUA_NUMBER_FMT        "%.14g"
> > > > is not long enough to do reversible conversions on doubles. I 
> > > > believe
> > > > you need %.19g for the conversion to be reversible.
> > >
> > > I think it's %.17g for IEEE doubles. (Despite what DBL_DIG says!)
> > > Lua was like that once, but then you get ugly things like this:
> > >
> > > > =string.format("%.17g",0.34)
> > > 0.34000000000000002
> > >
> > > > =0.34
> > > 0.34
> > >
> > > > =34/100
> > > 0.34
> > >
> > > Users complaint that this is an error in Lua! And it does not help 
> > > to point
> > > them to docs like http://lua-users.org/wiki/FloatingPoint ...