1 /* origin: FreeBSD /usr/src/lib/msun/src/e_atan2l.c */
3 * ====================================================
4 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
6 * Developed at SunSoft, a Sun Microsystems, Inc. business.
7 * Permission to use, copy, modify, and distribute this
8 * software is freely granted, provided that this notice
10 * ====================================================
14 * See comments in atan2.c.
15 * Converted to long double by David Schultz <das@FreeBSD.ORG>.
20 #if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
21 long double atan2l(long double y, long double x)
25 #elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384
26 #include "__invtrigl.h"
27 static const volatile long double
29 static const long double
30 pi = 3.14159265358979323846264338327950280e+00L;
32 long double atan2l(long double y, long double x)
34 union IEEEl2bits ux, uy;
37 int16_t exptx, expsignx, expty, expsigny;
40 expsigny = uy.xbits.expsign;
41 expty = expsigny & 0x7fff;
43 expsignx = ux.xbits.expsign;
44 exptx = expsignx & 0x7fff;
45 if ((exptx==BIAS+LDBL_MAX_EXP &&
46 ((ux.bits.manh&~LDBL_NBIT)|ux.bits.manl)!=0) || /* x is NaN */
47 (expty==BIAS+LDBL_MAX_EXP &&
48 ((uy.bits.manh&~LDBL_NBIT)|uy.bits.manl)!=0)) /* y is NaN */
50 if (expsignx==BIAS && ((ux.bits.manh&~LDBL_NBIT)|ux.bits.manl)==0) /* x=1.0 */
52 m = ((expsigny>>15)&1) | ((expsignx>>14)&2); /* 2*sign(x)+sign(y) */
55 if (expty==0 && ((uy.bits.manh&~LDBL_NBIT)|uy.bits.manl)==0) {
58 case 1: return y; /* atan(+-0,+anything)=+-0 */
59 case 2: return pi+tiny; /* atan(+0,-anything) = pi */
60 case 3: return -pi-tiny; /* atan(-0,-anything) =-pi */
64 if (exptx==0 && ((ux.bits.manh&~LDBL_NBIT)|ux.bits.manl)==0)
65 return expsigny < 0 ? -pio2_hi-tiny : pio2_hi+tiny;
67 if (exptx == BIAS+LDBL_MAX_EXP) {
68 if (expty == BIAS+LDBL_MAX_EXP) {
70 case 0: return pio2_hi*0.5+tiny; /* atan(+INF,+INF) */
71 case 1: return -pio2_hi*0.5-tiny; /* atan(-INF,+INF) */
72 case 2: return 1.5*pio2_hi+tiny; /*atan(+INF,-INF)*/
73 case 3: return -1.5*pio2_hi-tiny; /*atan(-INF,-INF)*/
77 case 0: return 0.0; /* atan(+...,+INF) */
78 case 1: return -0.0; /* atan(-...,+INF) */
79 case 2: return pi+tiny; /* atan(+...,-INF) */
80 case 3: return -pi-tiny; /* atan(-...,-INF) */
85 if (expty == BIAS+LDBL_MAX_EXP)
86 return expsigny < 0 ? -pio2_hi-tiny : pio2_hi+tiny;
90 if(k > LDBL_MANT_DIG+2) { /* |y/x| huge */
93 } else if (expsignx < 0 && k < -LDBL_MANT_DIG-2) /* |y/x| tiny, x<0 */
95 else /* safe to do y/x */
96 z = atanl(fabsl(y/x));
98 case 0: return z; /* atan(+,+) */
99 case 1: return -z; /* atan(-,+) */
100 case 2: return pi - (z-pi_lo); /* atan(+,-) */
101 default: /* case 3 */
102 return (z-pi_lo) - pi; /* atan(-,-) */