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From: steele@unc.UUCP
Newsgroups: comp.lang.c
Subject: Re: fabs(x) vs. (x) < 0 ? -(x) : (x)
Message-ID: <756@unc.unc.UUCP>
Date: Fri, 30-Jan-87 19:10:44 EST
Article-I.D.: unc.756
Posted: Fri Jan 30 19:10:44 1987
Date-Received: Sat, 31-Jan-87 19:39:57 EST
References: <4943@mimsy.UUCP> <2550005@hpisod2.HP>
Reply-To: steele@unc.UUCP (Oliver Steele)
Organization: CS Dept, U. of N. Carolina, Chapel Hill
Lines: 18

In article <2550005@hpisod2.HP> decot@hpisod2.HP (Dave Decot) writes:
>
>You could implement fabs() as a macro as follows:
>
>    #define fabs(X)     ((_fabs = (X)), (_fabs < 0? -_fabs : _fabs))
>
>if _fabs were declared as a float in the math library.

Beware
	fabs(a,fabs(b,c)),
as well as
	fabs(a,func(b,c))
where func is a macro which invokes fabs.
-- 

Oliver Steele----------------------------------steele@unc
"When a tree dies,	  ...!{decvax,ihnp4}!mcnc!unc!steele
plant another in its place."	steele%unc@csnet-relay.csnet