[Caml-list] Re: IEEE-754 (was: Easy solution in OCaml?)

[Christophe TROESTLER <debian00@tiscali.be>]

On Sat, 26 Apr 2003, Brian Hurt <brian.hurt@qlogic.com> wrote:
> 
> On Sat, 26 Apr 2003, Siegfried Gonzi wrote:
> 
> > dividing the two vectors:
> > (vector 0.0 0.0  23.34 23.4) through (vector 0.0 0.0 0.0 23.4)
> > 
> > (vector #f #f #f 1.0)
> 
> Hmm?  What platform are you on?  Linux on x86:
> 
> # let x = [ 0.0 ; 1.0 ; 0.0 ; 1.0 ]
>   and y = [ 0.0 ; 0.0 ; 1.0 ; 1.0 ] ;;

List.map2 ( /. ) x y

> - : float list = [nan.; inf.; 0.; 1.]

This is a feature of IEEE-754 arithmetic which means it should work
this way on virtually all architectures.

BTW, may I take this opportunity to advertise my little wishlist in
this respect ?  I'd like to have:

FAST is_nan : float -> bool 
     is_finite : float -> bool
               (I know it is possible to define them with
                classify_float but is is not fast)
and  copysign : float -> float -> float

Cheers,
ChriS

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