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From: sfk@otter.hpl.hp.com (Steve Knight)
Newsgroups: comp.lang.prolog
Subject: Re: arithmetic overflow checking
Message-ID: <1600022@otter.hpl.hp.com>
Date: 9 May 90 17:14:44 GMT
References: <870@cluster.cs.su.oz>
Organization: Hewlett-Packard Laboratories, Bristol, UK.
Lines: 16

Andrew Taylor writes:
> Some (most?) Prolog implementations do not check for overflow on
> (integer) arithemtic.  This doesn't seem acceptable to me.

I agree that it is unacceptable for an implementation to silently perform
incorrectly.  Even given Richard O'Keefe's comments on the difficulties 
of doing it, I would have expected the ability to turn on arithmetic-checking
at the very least.  Perhaps I am missing something .... ?

There are a couple of Prologs that avoid this problem by providing arbitrary
precision arithmetic.  As an example, Poplog Prolog offers the Common Lisp
model of arithmetic, which includes big integers, rationals, single and double
precision floats, and complex numbers -- together with the usual mathematical
functions (e.g. sin, cos, arcsin, sqrt, exp, log, ... ).
  
Steve