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/* from: FreeBSD: head/lib/msun/src/e_acosh.c 176451 2008-02-22 02:30:36Z das */
/* @(#)s_asinh.c 5.1 93/09/24 */
/*
* ====================================================
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
*
* Developed at SunPro, a Sun Microsystems, Inc. business.
* Permission to use, copy, modify, and distribute this
* software is freely granted, provided that this notice
* is preserved.
* ====================================================
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
/*
* See s_asinh.c for complete comments.
*
* Converted to long double by David Schultz <das@FreeBSD.ORG> and
* Bruce D. Evans.
*/
#include <float.h>
#ifdef __i386__
#include <ieeefp.h>
#endif
#include "fpmath.h"
#include "math.h"
#include "math_private.h"
/* EXP_LARGE is the threshold above which we use asinh(x) ~= log(2x). */
/* EXP_TINY is the threshold below which we use asinh(x) ~= x. */
#if LDBL_MANT_DIG == 64
#define EXP_LARGE 34
#define EXP_TINY -34
#elif LDBL_MANT_DIG == 113
#define EXP_LARGE 58
#define EXP_TINY -58
#else
#error "Unsupported long double format"
#endif
#if LDBL_MAX_EXP != 0x4000
/* We also require the usual expsign encoding. */
#error "Unsupported long double format"
#endif
#define BIAS (LDBL_MAX_EXP - 1)
static const double
one = 1.00000000000000000000e+00, /* 0x3FF00000, 0x00000000 */
huge= 1.00000000000000000000e+300;
#if LDBL_MANT_DIG == 64
static const union IEEEl2bits
u_ln2 = LD80C(0xb17217f7d1cf79ac, -1, 6.93147180559945309417e-1L);
#define ln2 u_ln2.e
#elif LDBL_MANT_DIG == 113
static const long double
ln2 = 6.93147180559945309417232121458176568e-1L; /* 0x162e42fefa39ef35793c7673007e6.0p-113 */
#else
#error "Unsupported long double format"
#endif
long double
asinhl(long double x)
{
long double t, w;
uint16_t hx, ix;
ENTERI();
GET_LDBL_EXPSIGN(hx, x);
ix = hx & 0x7fff;
if (ix >= 0x7fff) RETURNI(x+x); /* x is inf, NaN or misnormal */
if (ix < BIAS + EXP_TINY) { /* |x| < TINY, or misnormal */
if (huge + x > one) RETURNI(x); /* return x inexact except 0 */
}
if (ix >= BIAS + EXP_LARGE) { /* |x| >= LARGE, or misnormal */
w = logl(fabsl(x))+ln2;
} else if (ix >= 0x4000) { /* LARGE > |x| >= 2.0, or misnormal */
t = fabsl(x);
w = logl(2.0*t+one/(sqrtl(x*x+one)+t));
} else { /* 2.0 > |x| >= TINY, or misnormal */
t = x*x;
w =log1pl(fabsl(x)+t/(one+sqrtl(one+t)));
}
RETURNI((hx & 0x8000) == 0 ? w : -w);
}
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