(C) 1996 AROS - The Amiga Replacement OS
flags: zero : result is zero negative : result is negative overflow : 0
if (y_1 > pi/2 ) then y_1 = pi - y_1;
=> 0 <= y_1 < pi/2
Res = y - y^3/3! + y^5/5! - y^7/7! + y^9/9! - y^11/11! = = y(1+y^2(-1/3!+y^2(1/5!+y^2(-1/7!+y^2(1/9!-1/11!y^2)))));
if (y < 0) Res = -Res;
if (z was an odd number) Res = -Res;