[comp.sys.masscomp] ieee copysign

dale@lamont.UUCP (dale chayes) (03/15/89)

While porting some in-house code, I have come across a funtion in
the math.h include file called copysign(x,y) which returns x with the
sign of y. While this seems trivial, I wondered if it is significant?

The comments in Sun's include file say that these functions are
reccomended by IEEE, and sure enough they are. As a matter of fact,
copysign() is the first funtion in the appendix of ANSI/IEEE Std 754-1985
"Recommended Functions and Predicates."

The text (in the appendix) says:

	Copysign()x,y) returns x with the sign of y. Hence, 
	abs(x)=copysign(x,1.0), even it (sic) x is NaN.


It turns out, that there are a whole list of "recommended" funtcions in
the predicate that don't appear to be supplied by Concurrent/Masscomp.

I'm mostly a hardware guy (especially when it comes to this kind of
stuff.) Anyone got any clues?

Dale
------------------------------------------------------------------------


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Dale Chayes Lamont-Doherty Geological Observatory of Columbia University
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