From: skaller <skaller@ozemail.com.au>
To: Yaron Minsky <yminsky@cs.cornell.edu>
Cc: caml-list@inria.fr
Subject: Re: [Caml-list] Weird behavior with nan's and min/max
Date: 15 Oct 2003 09:43:43 +1000 [thread overview]
Message-ID: <1066175022.17727.9.camel@pelican> (raw)
In-Reply-To: <63219.141.155.88.179.1066164734.squirrel@minsky-primus.homeip.net>
On Wed, 2003-10-15 at 06:52, Yaron Minsky wrote:
> The second weirdness is the breaking of (==) => (=), since "nan == nan"
> evaluates to true and "nan = nan" evaluates to false.
The problem here is IEEE semantics, not Ocaml.
The idea that x = x isn't universally true is
mathemtically absurd.
One solution is to define a new float specific
IEEE conforming equality comparator
iEEE_eq : float -> float -> bool
and change the semantics of = to be mathematically
sound with
Nan = Nan ==> true
but possibly more expensive to evaluate.
This means that polymorphic comparisons agree with
monomorphic ones, and leaves it up to the numerical
programmer to use the monomorphic iEEE_eq comparison
it is needed. [Possibly the iEEE_eq function can be
given an infix symbol?]
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next prev parent reply other threads:[~2003-10-14 23:45 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-10-14 14:37 Yaron Minsky
2003-10-14 14:56 ` Yaron Minsky
2003-10-14 20:52 ` Yaron Minsky
2003-10-14 23:43 ` skaller [this message]
2003-10-16 17:29 ` Hendrik Tews
2003-10-16 13:16 ` Xavier Leroy
2003-10-16 14:01 ` Yaron Minsky
2003-10-17 9:26 ` [Caml-list] Test nan (was: Weird behavior with nan's and min/max) Christophe TROESTLER
2003-10-16 21:40 ` [Caml-list] Weird behavior with nan's and min/max Yaron Minsky
2003-10-16 21:50 ` Yaron Minsky
2003-10-16 22:52 ` Damien Doligez
2003-10-17 14:55 ` skaller
2003-10-17 15:14 ` Floating point exceptions (Was Re: [Caml-list] Weird behavior with nan's and min/max) Yaron Minsky
2003-10-17 23:55 ` [Caml-list] Weird behavior with nan's and min/max Yaron M. Minsky
2003-10-20 13:29 ` Xavier Leroy
2003-10-20 13:43 ` Yaron Minsky
2003-10-20 14:24 ` Xavier Leroy
2003-10-16 23:55 ` [Caml-list] " Jed Davis
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