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"
26 #define ACOS_CONST (BIAS - 65) /* 2**-65 */
28 long double acosl(long double x)
31 long double z, p, q, r, w, s, c, df;
32 int16_t expsign, expt;
34 expsign = u.xbits.expsign;
35 expt = expsign & 0x7fff;
36 if (expt >= BIAS) { /* |x| >= 1 */
38 ((u.bits.manh & ~LDBL_NBIT) | u.bits.manl) == 0) {
40 return 0.0; /* acos(1) = 0 */
43 return pi_hi + 2.0 * pio2_lo; /* acos(-1)= pi */
45 return (x - x) / (x - x); /* acos(|x|>1) is NaN */
47 if (expt < BIAS - 1) { /* |x| < 0.5 */
48 if (expt < ACOS_CONST)
49 return pio2_hi + pio2_lo; /* x tiny: acosl=pi/2 */
54 return pio2_hi - (x - (pio2_lo - x * r));
55 } else if (expsign < 0) { /* x < -0.5 */
62 return pi_hi - 2.0 * (s + w);
63 } else { /* x > 0.5 */
69 c = (z - df * df) / (s + df);
74 return 2.0 * (df + w);