trig functions

[Lance M. Optican - LMO]

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Date: 12 Nov 90 15:48:57 GMT
From: "Allan R. Wilks" <uunet!ucbvax.berkeley.edu!alice!allan>
Organization: AT&T Bell Laboratories, Murray Hill NJ
Subject: trig functions
Message-Id: <11609 at alice.att.com>
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Status: R


Is it reasonable to expect the cosine of (exactly) 0 to be (exactly) 1?

$ cat > a.c <<!
#include <math.h>
main()
{
	printf("%g\n", 1.0-cos(0.0));
}
!
$ cc a.c -lm
$ a.out
1.11022e-16
$ cc a.c -lm43
$ a.out
0

Allan R. Wilks
AT&T Bell Labs
allan at research.att.com


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It is reasonable to expect the maht library to perform well!  I
tried Allan Wilks program on both Sun/3 and Sun/4 machines, and
they both gave "0" as the difference between 1.0 and cos(0.0).
Who at SGI is responsible for the math library?  What standards
of compatibility are enforced with other machine architectures?

---------------------------------------------------+-----------------------
	Lance M. Optican			   |	uunet!lsr-vax!lmo 
	National Eye Institute, NIH, Bethesda, MD  |	(301) 496-3549    
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