Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!zaphod.mps.ohio-state.edu!pacific.mps.ohio-state.edu!linac!att!att!dptg!ulysses!andante!alice!allan
From: allan@alice.att.com (Allan R. Wilks)
Newsgroups: comp.sys.sgi
Subject: trig functions
Keywords: math library
Message-ID: <11609@alice.att.com>
Date: 12 Nov 90 15:48:57 GMT
Organization: AT&T Bell Laboratories, Murray Hill NJ
Lines: 20


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@research.att.com