mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-22 21:10:07 +00:00
37d83a089d
Similar to various other bugs in this area, some tanh implementations do not raise the underflow exception for subnormal arguments, when the result is tiny and inexact. This patch forces the exception in a similar way to previous fixes. Tested for x86_64, x86, mips64 and powerpc. [BZ #16520] * sysdeps/ieee754/dbl-64/s_tanh.c: Include <float.h>. (__tanh): Force underflow exception for arguments with small absolute value. * sysdeps/ieee754/flt-32/s_tanhf.c: Include <float.h>. (__tanhf): Force underflow exception for arguments with small absolute value. * sysdeps/ieee754/ldbl-128/s_tanhl.c: Include <float.h>. (__tanhl): Force underflow exception for arguments with small absolute value. * sysdeps/ieee754/ldbl-128ibm/s_tanhl.c: Include <float.h>. (__tanhl): Force underflow exception for arguments with small absolute value. * sysdeps/ieee754/ldbl-96/s_tanhl.c: Include <float.h>. (__tanhl): Force underflow exception for arguments with small absolute value. * math/auto-libm-test-in: Add more tests of tanh. * math/auto-libm-test-out: Regenerated. * sysdeps/i386/fpu/libm-test-ulps: Update.
103 lines
2.5 KiB
C
103 lines
2.5 KiB
C
/* @(#)s_tanh.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.
|
|
* ====================================================
|
|
*/
|
|
|
|
#if defined(LIBM_SCCS) && !defined(lint)
|
|
static char rcsid[] = "$NetBSD: s_tanh.c,v 1.7 1995/05/10 20:48:22 jtc Exp $";
|
|
#endif
|
|
|
|
/* Tanh(x)
|
|
* Return the Hyperbolic Tangent of x
|
|
*
|
|
* Method :
|
|
* x -x
|
|
* e - e
|
|
* 0. tanh(x) is defined to be -----------
|
|
* x -x
|
|
* e + e
|
|
* 1. reduce x to non-negative by tanh(-x) = -tanh(x).
|
|
* 2. 0 <= x <= 2**-55 : tanh(x) := x*(one+x)
|
|
* -t
|
|
* 2**-55 < x <= 1 : tanh(x) := -----; t = expm1(-2x)
|
|
* t + 2
|
|
* 2
|
|
* 1 <= x <= 22.0 : tanh(x) := 1- ----- ; t=expm1(2x)
|
|
* t + 2
|
|
* 22.0 < x <= INF : tanh(x) := 1.
|
|
*
|
|
* Special cases:
|
|
* tanh(NaN) is NaN;
|
|
* only tanh(0)=0 is exact for finite argument.
|
|
*/
|
|
|
|
#include <float.h>
|
|
#include <math.h>
|
|
#include <math_private.h>
|
|
|
|
static const double one = 1.0, two = 2.0, tiny = 1.0e-300;
|
|
|
|
double
|
|
__tanh (double x)
|
|
{
|
|
double t, z;
|
|
int32_t jx, ix, lx;
|
|
|
|
/* High word of |x|. */
|
|
EXTRACT_WORDS (jx, lx, x);
|
|
ix = jx & 0x7fffffff;
|
|
|
|
/* x is INF or NaN */
|
|
if (ix >= 0x7ff00000)
|
|
{
|
|
if (jx >= 0)
|
|
return one / x + one; /* tanh(+-inf)=+-1 */
|
|
else
|
|
return one / x - one; /* tanh(NaN) = NaN */
|
|
}
|
|
|
|
/* |x| < 22 */
|
|
if (ix < 0x40360000) /* |x|<22 */
|
|
{
|
|
if ((ix | lx) == 0)
|
|
return x; /* x == +-0 */
|
|
if (ix < 0x3c800000) /* |x|<2**-55 */
|
|
{
|
|
if (fabs (x) < DBL_MIN)
|
|
{
|
|
double force_underflow = x * x;
|
|
math_force_eval (force_underflow);
|
|
}
|
|
return x * (one + x); /* tanh(small) = small */
|
|
}
|
|
if (ix >= 0x3ff00000) /* |x|>=1 */
|
|
{
|
|
t = __expm1 (two * fabs (x));
|
|
z = one - two / (t + two);
|
|
}
|
|
else
|
|
{
|
|
t = __expm1 (-two * fabs (x));
|
|
z = -t / (t + two);
|
|
}
|
|
/* |x| > 22, return +-1 */
|
|
}
|
|
else
|
|
{
|
|
z = one - tiny; /* raised inexact flag */
|
|
}
|
|
return (jx >= 0) ? z : -z;
|
|
}
|
|
weak_alias (__tanh, tanh)
|
|
#ifdef NO_LONG_DOUBLE
|
|
strong_alias (__tanh, __tanhl)
|
|
weak_alias (__tanh, tanhl)
|
|
#endif
|