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From: ik.naggum-erik@siri.uio.no
Newsgroups: comp.os.vms
Subject: Re: C help
Message-ID: <6129.8707122222@verdande.UIO.NO>
Date: Wed, 15-Jul-87 10:59:14 EDT
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Posted: Wed Jul 15 10:59:14 1987
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"The best way to predict the future is to invent it." (EVB S/W Eng, Inc.)
Message-ID: <12317866627.139.IK.NAGGUM-ERIK@SIRI>


Yates@a.chem.upenn.edu writes:
> C makes me nervous! Below is an example of the dangers involved with
> Floating point square roots. Is something wrong here or does one just
> have to be extremely careful in C with:
 ......
> Is there a bug here or is it just that C must never, ever be treated
> as a high level language for floating point operations?
 ......
> $! The following logicals allow /G_Float qualifier to be used
> $! with the CC command and Curses (a screen management package)
> $! according to the C manual, anyway
 ......
> Is it any wonder I keep putting away my K and R? John

John,

I regard myself as an expert in C and Unix.  I have read the Ansi Standard Draft of 10/10/86, and Kernighan and
Richie: The C Programming Language.  With 3 years of experience in C
programming, and 200K source lines on my conscience, I have some
comments to your article, blaming C for various flaws in floating point
operations on a VAX (model X?), using VAX C version 2.2 under VMS.

I took the time to go through a lot of documentation tonight, and
visited those for (AT&T) Unix Version 7, System III and System V, for
SVID, for BSD release 4.3 and Ultrix 2.0, for XENIX 3 and XENIX 5, and
finally those of SUN OS.  (Insert list of trademark owners here.)

Nowhere can I find a reference to G-floating or, in fact, any other
specific implementation of floating point numbers, as part of the C
language.  Rather, I have found that each machine and each implementor
decides which formats to use, and that they are more an attribute of the
hardware than of the language definition.

You ask,
> Is it any wonder I keep putting away my K and R?

Why not put away your VAX VMS or your VAX C, instead?

Erik Naggum		ARPA:  enag@siri.uio.no or enag%siri@ifi.uio.no
Manager			SNAIL: POB 1560 Vika, N-0118 OSLO 1, NORWAY
Naggum Software		PHONE: (intl)+47-2-549-163  (0600-1200 GMT)
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