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-rw-r--r--newlib/libm/math/s_tanh.c128
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diff --git a/newlib/libm/math/s_tanh.c b/newlib/libm/math/s_tanh.c
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-
-/* @(#)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.
- * ====================================================
- */
-
-/*
-
-FUNCTION
- <<tanh>>, <<tanhf>>---hyperbolic tangent
-
-INDEX
-tanh
-INDEX
-tanhf
-
-ANSI_SYNOPSIS
- #include <math.h>
- double tanh(double <[x]>);
- float tanhf(float <[x]>);
-
-TRAD_SYNOPSIS
- #include <math.h>
- double tanh(<[x]>)
- double <[x]>;
-
- float tanhf(<[x]>)
- float <[x]>;
-
-
-DESCRIPTION
-
-<<tanh>> computes the hyperbolic tangent of
-the argument <[x]>. Angles are specified in radians.
-
-<<tanh(<[x]>)>> is defined as
-. sinh(<[x]>)/cosh(<[x]>)
-
-<<tanhf>> is identical, save that it takes and returns <<float>> values.
-
-RETURNS
-The hyperbolic tangent of <[x]> is returned.
-
-PORTABILITY
-<<tanh>> is ANSI C. <<tanhf>> is an extension.
-
-*/
-
-/* 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 "fdlibm.h"
-
-#ifndef _DOUBLE_IS_32BITS
-
-#ifdef __STDC__
-static const double one=1.0, two=2.0, tiny = 1.0e-300;
-#else
-static double one=1.0, two=2.0, tiny = 1.0e-300;
-#endif
-
-#ifdef __STDC__
- double tanh(double x)
-#else
- double tanh(x)
- double x;
-#endif
-{
- double t,z;
- __int32_t jx,ix;
-
- /* High word of |x|. */
- GET_HIGH_WORD(jx,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<0x3c800000) /* |x|<2**-55 */
- 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;
-}
-
-#endif /* _DOUBLE_IS_32BITS */