1 /* origin: FreeBSD /usr/src/lib/msun/src/e_acosl.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 * ====================================================
13 * See comments in acos.c.
14 * Converted to long double by David Schultz <das@FreeBSD.ORG>.
19 #if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
20 long double acosl(long double x)
24 #elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384
25 #include "__invtrigl.h"
27 static const long double
28 one = 1.00000000000000000000e+00;
32 /* XXX Work around the fact that gcc truncates long double constants on i386 */
33 static volatile double
34 pi1 = 3.14159265358979311600e+00, /* 0x1.921fb54442d18p+1 */
35 pi2 = 1.22514845490862001043e-16; /* 0x1.1a80000000000p-53 */
36 #define pi ((long double)pi1 + pi2)
39 static const long double
40 pi = 3.14159265358979323846264338327950280e+00L;
43 long double acosl(long double x)
46 long double z, p, q, r, w, s, c, df;
47 int16_t expsign, expt;
49 expsign = u.xbits.expsign;
50 expt = expsign & 0x7fff;
51 if (expt >= BIAS) { /* |x| >= 1 */
53 ((u.bits.manh & ~LDBL_NBIT) | u.bits.manl) == 0) {
55 return 0.0; /* acos(1) = 0 */
57 return pi + 2.0 * pio2_lo; /* acos(-1)= pi */
59 return (x - x) / (x - x); /* acos(|x|>1) is NaN */
61 if (expt < BIAS - 1) { /* |x| < 0.5 */
62 if (expt < ACOS_CONST)
63 return pio2_hi + pio2_lo; /* x tiny: acosl=pi/2 */
68 return pio2_hi - (x - (pio2_lo - x * r));
69 } else if (expsign < 0) { /* x < -0.5 */
76 return pi - 2.0 * (s + w);
77 } else { /* x > 0.5 */
83 c = (z - df * df) / (s + df);
88 return 2.0 * (df + w);