fabs(x) vs. (x) < 0 ? -(x) : (x)

[steele at unc.UUCP]

In article <2550005 at hpisod2.HP> decot at 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 at unc
"When a tree dies,	  ...!{decvax,ihnp4}!mcnc!unc!steele
plant another in its place."	steele%unc at csnet-relay.csnet