- case 0: return pi_o_4+tiny; /* atan(+INF,+INF) */
- case 1: return -pi_o_4-tiny; /* atan(-INF,+INF) */
- case 2: return 3.0*pi_o_4+tiny; /* atan(+INF,-INF) */
- case 3: return -3.0*pi_o_4-tiny; /* atan(-INF,-INF) */
+ case 0: return pi/4; /* atan(+INF,+INF) */
+ case 1: return -pi/4; /* atan(-INF,+INF) */
+ case 2: return 3*pi/4; /* atan(+INF,-INF) */
+ case 3: return -3*pi/4; /* atan(-INF,-INF) */