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"
28 static const volatile long double tiny = 1.0e-300;
30 long double atan2l(long double y, long double x)
32 union IEEEl2bits ux, uy;
35 int16_t exptx, expsignx, expty, expsigny;
38 expsigny = uy.xbits.expsign;
39 expty = expsigny & 0x7fff;
41 expsignx = ux.xbits.expsign;
42 exptx = expsignx & 0x7fff;
43 if ((exptx==BIAS+LDBL_MAX_EXP &&
44 ((ux.bits.manh&~LDBL_NBIT)|ux.bits.manl)!=0) || /* x is NaN */
45 (expty==BIAS+LDBL_MAX_EXP &&
46 ((uy.bits.manh&~LDBL_NBIT)|uy.bits.manl)!=0)) /* y is NaN */
48 if (expsignx==BIAS && ((ux.bits.manh&~LDBL_NBIT)|ux.bits.manl)==0) /* x=1.0 */
50 m = ((expsigny>>15)&1) | ((expsignx>>14)&2); /* 2*sign(x)+sign(y) */
53 if (expty==0 && ((uy.bits.manh&~LDBL_NBIT)|uy.bits.manl)==0) {
56 case 1: return y; /* atan(+-0,+anything)=+-0 */
57 case 2: return pi_hi+tiny; /* atan(+0,-anything) = pi */
58 case 3: return -pi_hi-tiny; /* atan(-0,-anything) =-pi */
62 if (exptx==0 && ((ux.bits.manh&~LDBL_NBIT)|ux.bits.manl)==0)
63 return expsigny < 0 ? -pio2_hi-tiny : pio2_hi+tiny;
65 if (exptx == BIAS+LDBL_MAX_EXP) {
66 if (expty == BIAS+LDBL_MAX_EXP) {
68 case 0: return pio2_hi*0.5+tiny; /* atan(+INF,+INF) */
69 case 1: return -pio2_hi*0.5-tiny; /* atan(-INF,+INF) */
70 case 2: return 1.5*pio2_hi+tiny; /* atan(+INF,-INF) */
71 case 3: return -1.5*pio2_hi-tiny; /* atan(-INF,-INF) */
75 case 0: return 0.0; /* atan(+...,+INF) */
76 case 1: return -0.0; /* atan(-...,+INF) */
77 case 2: return pi_hi+tiny; /* atan(+...,-INF) */
78 case 3: return -pi_hi-tiny; /* atan(-...,-INF) */
83 if (expty == BIAS+LDBL_MAX_EXP)
84 return expsigny < 0 ? -pio2_hi-tiny : pio2_hi+tiny;
88 if(k > LDBL_MANT_DIG+2) { /* |y/x| huge */
91 } else if (expsignx < 0 && k < -LDBL_MANT_DIG-2) /* |y/x| tiny, x<0 */
93 else /* safe to do y/x */
94 z = atanl(fabsl(y/x));
96 case 0: return z; /* atan(+,+) */
97 case 1: return -z; /* atan(-,+) */
98 case 2: return pi_hi-(z-pi_lo); /* atan(+,-) */
100 return (z-pi_lo)-pi_hi; /* atan(-,-) */