fp bug?

[utzoo!decvax!duke!mcnc!swd]

On our 11/70, this program

	double cos();
	main() {
		printf("%20.20f\n", cos(0.0));
	}

prints out
	1.00000000000000000000
On our VAX 11/780, it prints
	1.00000000000000010000

We are not amused.

Has anyone else encountered this problem and/or
fixed it?
We have compared the cos routine on the 11 and the 780
and they are identical.