ipiq: Add simple IPI latency measure sysctls (2)
[dragonfly.git] / lib / libm / src / e_atanhl.c
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a8a6a916
JM
1/* from: FreeBSD: head/lib/msun/src/e_atanh.c 176451 2008-02-22 02:30:36Z das */
2
3/* @(#)e_atanh.c 1.3 95/01/18 */
4/*
5 * ====================================================
6 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
7 *
8 * Developed at SunSoft, a Sun Microsystems, Inc. business.
9 * Permission to use, copy, modify, and distribute this
10 * software is freely granted, provided that this notice
11 * is preserved.
12 * ====================================================
13 *
14 * $FreeBSD: head/lib/msun/src/e_atanhl.c 251599 2013-06-10 06:04:58Z das $
15 */
16
17/*
18 * See e_atanh.c for complete comments.
19 *
20 * Converted to long double by David Schultz <das@FreeBSD.ORG> and
21 * Bruce D. Evans.
22 */
23
24#include <float.h>
25#ifdef __i386__
26#include <ieeefp.h>
27#endif
28
29#include "fpmath.h"
30#include "math.h"
31#include "math_private.h"
32
33/* EXP_TINY is the threshold below which we use atanh(x) ~= x. */
34#if LDBL_MANT_DIG == 64
35#define EXP_TINY -34
36#elif LDBL_MANT_DIG == 113
37#define EXP_TINY -58
38#else
39#error "Unsupported long double format"
40#endif
41
42#if LDBL_MAX_EXP != 0x4000
43/* We also require the usual expsign encoding. */
44#error "Unsupported long double format"
45#endif
46
47#define BIAS (LDBL_MAX_EXP - 1)
48
49static const double one = 1.0, huge = 1e300;
50static const double zero = 0.0;
51
52long double
53atanhl(long double x)
54{
55 long double t;
56 uint16_t hx, ix;
57
58 ENTERI();
59 GET_LDBL_EXPSIGN(hx, x);
60 ix = hx & 0x7fff;
61 if (ix >= 0x3fff) /* |x| >= 1, or NaN or misnormal */
62 RETURNI(fabsl(x) == 1 ? x / zero : (x - x) / (x - x));
63 if (ix < BIAS + EXP_TINY && (huge + x) > zero)
64 RETURNI(x); /* x is tiny */
65 SET_LDBL_EXPSIGN(x, ix);
66 if (ix < 0x3ffe) { /* |x| < 0.5, or misnormal */
67 t = x+x;
68 t = 0.5*log1pl(t+t*x/(one-x));
69 } else
70 t = 0.5*log1pl((x+x)/(one-x));
71 RETURNI((hx & 0x8000) == 0 ? t : -t);
72}