Numerics question: reading floating point constants
Milan Zimmermann
milan.zimmermann at sympatico.ca
Tue Apr 25 05:19:15 UTC 2006
On 2006 April 9 12:23, stéphane ducasse wrote:
> Do you know a good book or lectures on the problems related to number
> representation in our nice
> computers?
Perhaps the best resource is the web site of William Kahan, "father" of IEEE
754 here:
http://www.cs.berkeley.edu/~wkahan/
It is a fascinating read about the IEEE-754 battle. On the bottom of his site,
he has recent (extremely interesting) articles, this is just one example:
http://www.cs.berkeley.edu/~wkahan/ARITH_17.pdf
In all those recent articles, he is describing the efforts to maintain
hardware manufacturer's interest to support IEEE 754 while software support
is lagging badly, even 20 years later, apparently only C99 and Fortran
(2000something) are compliant, Cell chips have already sacrificed their
hardware support, and other interesting stuff. It really feels sad for this
industry ... but anyway, that seems the best place to look.
Also this site is interesting:
http://babbage.cs.qc.edu/
In terms of books, perhaps this:
http://www.cs.nyu.edu/overton/book/
(but I did not read it)
I was looking for software that would test how much a language (libraries)
adhere to IEEE754, thinking it would be interesting to translate to Squeak,
there is stuff like:
http://www.tybor.com/
But I run out of understanding (and time)
Sorry to flood with links, I was just recently reading about this stuff and
saved it all on Flock :)
Milan
>
> Stef
>
> On 9 avr. 06, at 18:18, nicolas cellier wrote:
> > 1 point for Andres, conversion from base 10 to base 2 is inexact.
> >
> > 1 point for Boris : successive inexact operations are not only
> > costly, they
> > can degrade accuracy.
> >
> > I wonder if the conversion shouldn't be made with respect to IEEE
> > rounding
> > mode, and if i remember, this rounding mode is a parameter of
> > underlying
> > hardware.
> >
> > In the past, i tried several algo. and finally, i lazily decided to
> > use a call
> > to sprintf/sscan from within VW.
> > But with a good reference such as Tony's (1 point) we should make
> > it in
> > Smalltalk.
> >
> > Nicolas
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