1 /* e_atan2f.c -- float version of e_atan2.c.
2 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
6 * ====================================================
7 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
9 * Developed at SunPro, a Sun Microsystems, Inc. business.
10 * Permission to use, copy, modify, and distribute this
11 * software is freely granted, provided that this notice
13 * ====================================================
17 #include "math_private.h"
23 pi_o_4 = 7.8539818525e-01, /* 0x3f490fdb */
24 pi_o_2 = 1.5707963705e+00, /* 0x3fc90fdb */
25 pi = 3.1415927410e+00; /* 0x40490fdb */
27 pi_lo = -8.7422776573e-08; /* 0xb3bbbd2e */
30 atan2f(float y, float x)
33 int32_t k,m,hx,hy,ix,iy;
40 (iy>0x7f800000)) /* x or y is NaN */
42 if(hx==0x3f800000) return atanf(y); /* x=1.0 */
43 m = ((hy>>31)&1)|((hx>>30)&2); /* 2*sign(x)+sign(y) */
49 case 1: return y; /* atan(+-0,+anything)=+-0 */
50 case 2: return pi+tiny;/* atan(+0,-anything) = pi */
51 case 3: return -pi-tiny;/* atan(-0,-anything) =-pi */
55 if(ix==0) return (hy<0)? -pi_o_2-tiny: pi_o_2+tiny;
61 case 0: return pi_o_4+tiny;/* atan(+INF,+INF) */
62 case 1: return -pi_o_4-tiny;/* atan(-INF,+INF) */
63 case 2: return (float)3.0*pi_o_4+tiny;/*atan(+INF,-INF)*/
64 case 3: return (float)-3.0*pi_o_4-tiny;/*atan(-INF,-INF)*/
68 case 0: return zero ; /* atan(+...,+INF) */
69 case 1: return -zero ; /* atan(-...,+INF) */
70 case 2: return pi+tiny ; /* atan(+...,-INF) */
71 case 3: return -pi-tiny ; /* atan(-...,-INF) */
76 if(iy==0x7f800000) return (hy<0)? -pi_o_2-tiny: pi_o_2+tiny;
80 if(k > 26) { /* |y/x| > 2**26 */
81 z=pi_o_2+(float)0.5*pi_lo;
84 else if(k<-26&&hx<0) z=0.0; /* 0 > |y|/x > -2**-26 */
85 else z=atanf(fabsf(y/x)); /* safe to do y/x */
87 case 0: return z ; /* atan(+,+) */
88 case 1: return -z ; /* atan(-,+) */
89 case 2: return pi-(z-pi_lo);/* atan(+,-) */
91 return (z-pi_lo)-pi;/* atan(-,-) */