mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-18 19:10:06 +00:00
85 lines
2.1 KiB
C
85 lines
2.1 KiB
C
/* s_atanhl.c -- long double version of s_atan.c.
|
|
* Conversion to long double by Ulrich Drepper,
|
|
* Cygnus Support, drepper@cygnus.com.
|
|
*/
|
|
|
|
/*
|
|
* ====================================================
|
|
* 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.
|
|
* ====================================================
|
|
*/
|
|
|
|
#if defined(LIBM_SCCS) && !defined(lint)
|
|
static char rcsid[] = "$NetBSD: $";
|
|
#endif
|
|
|
|
/* __ieee754_atanhl(x)
|
|
* Method :
|
|
* 1.Reduced x to positive by atanh(-x) = -atanh(x)
|
|
* 2.For x>=0.5
|
|
* 1 2x x
|
|
* atanhl(x) = --- * log(1 + -------) = 0.5 * log1p(2 * --------)
|
|
* 2 1 - x 1 - x
|
|
*
|
|
* For x<0.5
|
|
* atanhl(x) = 0.5*log1pl(2x+2x*x/(1-x))
|
|
*
|
|
* Special cases:
|
|
* atanhl(x) is NaN if |x| > 1 with signal;
|
|
* atanhl(NaN) is that NaN with no signal;
|
|
* atanhl(+-1) is +-INF with signal.
|
|
*
|
|
*/
|
|
|
|
#include "math.h"
|
|
#include "math_private.h"
|
|
|
|
#ifdef __STDC__
|
|
static const long double one = 1.0L, huge = 1e4900L;
|
|
#else
|
|
static long double one = 1.0L, huge = 1e4900L;
|
|
#endif
|
|
|
|
#ifdef __STDC__
|
|
static const long double zero = 0.0L;
|
|
#else
|
|
static double long zero = 0.0L;
|
|
#endif
|
|
|
|
#ifdef __STDC__
|
|
long double __ieee754_atanhl(long double x)
|
|
#else
|
|
long double __ieee754_atanhl(x)
|
|
long double x;
|
|
#endif
|
|
{
|
|
long double t;
|
|
u_int32_t jx, ix;
|
|
ieee854_long_double_shape_type u;
|
|
|
|
u.value = x;
|
|
jx = u.parts32.w0;
|
|
ix = jx & 0x7fffffff;
|
|
u.parts32.w0 = ix;
|
|
if (ix >= 0x3fff0000) /* |x| >= 1.0 or infinity or NaN */
|
|
{
|
|
if (u.value == one)
|
|
return x/zero;
|
|
else
|
|
return (x-x)/(x-x);
|
|
}
|
|
if(ix<0x3fc60000 && (huge+x)>zero) return x; /* x < 2^-57 */
|
|
|
|
if(ix<0x3ffe0000) { /* x < 0.5 */
|
|
t = u.value+u.value;
|
|
t = 0.5*__log1pl(t+t*u.value/(one-u.value));
|
|
} else
|
|
t = 0.5*__log1pl((u.value+u.value)/(one-u.value));
|
|
if(jx & 0x80000000) return -t; else return t;
|
|
}
|