Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!yale!mintaka!bloom-beacon!eru!luth!sunic!sics.se!sics.se!roland
From: roland@sics.se (Roland Karlsson)
Newsgroups: comp.lang.prolog
Subject: Re: Sicstus Prolog Questions
Message-ID: <1990Jul24.111727.14354@sics.se>
Date: 24 Jul 90 11:17:27 GMT
References: <5574@uceng.UC.EDU>
Sender: news@sics.se
Organization: Swedish Institute of Computer Science, Kista
Lines: 38
In-Reply-To: ranga@uceng.UC.EDU's message of 22 Jul 90 11:09:12 GMT


> For example,  here is a simple psuedo random number generator.
> IX is the seed.  This produced about 700 to 800 random numbers correctly 
> (I checked them through other means) and then started giving out 0's;
> The reason, I found through tracing, invariably was an underflow/overlow.
> At that point, the prolog system wouldn't do even simple arithmetic 
> properly: for eg, `A is 1/6' produces `A = 4.32583271660369e-308' !!!

Yes there have been some bugs in previous versions of number crunching.
This bug is no more.  By the way, SICStus no longer use table lookup
for numbers.  Numbers are stored on the heap.

> As one way of avoiding the above problem, I have tried to implementing
> my floating point routines in C and tried to interface them using
> the foreign language interface feature of Sisctus.  I couldn't get
> that working either.  'load_foreign_files' gives me either
> an 'illegal usage' message or says 'myCfile.o undefined'.
> 'foreign' and 'foreign_file' also give 'illegal usage' messages.

As I not have seen your code it is impossible to tell why the
foreign_interface do not work.  It works for me.  Maybe you have an old
version of SICStus or maybe you are doing something wrong.

Current version is:
SICStus 0.6 #18: Wed Jul 11 20:00:53 MET DST 1990


Roland Karlsson

PS. The best way to get answers concerning SICStus Prolog is to write
    to matsc@sics.se (Mats Carlsson).  He is on vacation but will be back
    in a couple of weeks.  He always answers promptly and is more than
    glad to know about bugs (:-).
DS.
--
Roland Karlsson
SICS, PO Box 1263, S-164 28 KISTA, SWEDEN	Internet: roland@sics.se
Tel: +46 8 752 15 40	Ttx: 812 61 54 SICS S	Fax: +46 8 751 72 30