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[Caml-list] Finding the sign of a float
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Date: -- (:)
From: Shawn Wagner <shawnw@s...>
Subject: Re: [Caml-list] Finding the sign of a float
On Sat, Feb 01, 2003 at 05:11:10PM +0300, malc wrote:
> On Sat, 1 Feb 2003, John Carr wrote:
> 
> >
> > > I'm looking for a way, in pure ocaml without having to bail out to C, to
> > > tell if a float is negative or not.
> > >
> > > Just using x < 0.0 won't work, as I need to be able to tell the difference
> > > between -0.0 and +0.0. This is for ocaml versions of the C copysign and
> > > signbit functions. Any suggestions?
> >
> > x < 0.0 || (x = 0.0 && 1.0/.x < 0.0)
> >
> > may be faster than converting the bits to integer, or slower,
> > depending on platform and context, and how often you encounter -0.
> 
> 1.0 /. x = neg_infinity less typing
> 

That one doesn't work for all negative numbers, though. I think I'll go
with John's, though Chris's suggestion of converting to an int64 is nifty. I
wasn't aware of bits_to_float before.

PS: I agree with Chris's sentiments about overloaded arithmetic operators
(It has to be possible; < > and = do it...) and largeint constants. That
last one is particularily annoying, as I never could figure out how to make
my patch to add them work with camlp4.

-- 
Shawn Wagner
shawnw@speakeasy.org
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