Erik Bertelsen wrote:

[..]

> You've got it, Giles !

[..]

> Between the two calls of a.out, I reinstalled libm in a version, where I
> reverted the change in line 78 made in October, i.e. by removing
> the () that was added to silence the compiler with WARNS=1.
> 
> 49 cvs diff -r 1.1.1.1 e_atan2.c 
> Index: e_atan2.c
> ===================================================================
> RCS file: /sw/cvs-base/src/lib/libm/src/e_atan2.c,v
> retrieving revision 1.1.1.1
> retrieving revision 1.1.1.2
> diff -r1.1.1.1 -r1.1.1.2
> 12a13
> > #include <sys/cdefs.h>
> 14c15
> < static char rcsid[] = "$NetBSD: e_atan2.c,v 1.8 1995/05/10 20:44:51 jtc
> Exp $";
> ---
> > __RCSID("$NetBSD: e_atan2.c,v 1.9 1997/10/09 11:28:40 lukem Exp $");
> 77c78
> <       if((hx-0x3ff00000|lx)==0) return atan(y);   /* x=1.0 */
> ---
> >       if((hx-(0x3ff00000|lx))==0) return atan(y);   /* x=1.0 */
> 
> 
> 
> What's lukem's (and others) opinion -- should it really be
> 
>          if (((hx-0x3ff00000)|lx)==0) return atan(y);

Certainly making that change gives 0.694738276196703 once again. What
an excellent piece of detective work! Well done everyone,

 Patrick