Path: utzoo!attcan!uunet!mcvax!cernvax!hjm
From: hjm@cernvax.UUCP (Hubert Matthews)
Newsgroups: comp.lang.fortran
Subject: Re: Fortran versus C for numerical analysis
Message-ID: <820@cernvax.UUCP>
Date: 13 Sep 88 15:47:58 GMT
References: <893@amelia.nas.nasa.gov> <3064@lanl.gov>
Reply-To: hjm@cernvax.UUCP (Hubert Matthews)
Organization: CERN European Laboratory for Particle Physics, CH-1211 Geneva, Switzerland
Lines: 16


Consider the following cases:

      I = (5 / 4) * 5		(I gets 5)

      I = 5 / (4 * 5)		(I gets 0)

      I = 5 / 4 * 5		(I gets 5 in F77, I gets something in C)

Personally, I wouldn't use case 3; I would always enforce an evaluation order
by using parentheses.  If this could be ambiguous in C, I wouldn't use it for
numerical work.  The same problem occurs when using mixed-mode arithmetic.
Evaluation order is important, and parentheses are the most obvious way of
expressing it.  Temporary variables are a hack.

	Hubert Matthews