GCC Code Coverage Report
Directory: ./ Exec Total Coverage
File: lib/libm/src/ld80/s_tanhl.c Lines: 0 17 0.0 %
Date: 2017-11-13 Branches: 0 14 0.0 %

Line Branch Exec Source
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/* @(#)s_tanh.c 5.1 93/09/24 */
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/*
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 * ====================================================
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 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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 *
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 * Developed at SunPro, a Sun Microsystems, Inc. business.
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 * Permission to use, copy, modify, and distribute this
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 * software is freely granted, provided that this notice
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 * is preserved.
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 * ====================================================
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 */
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/* tanhl(x)
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 * Return the Hyperbolic Tangent of x
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 *
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 * Method :
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 *				        x    -x
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 *				       e  - e
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 *	0. tanhl(x) is defined to be -----------
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 *				        x    -x
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 *				       e  + e
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 *	1. reduce x to non-negative by tanhl(-x) = -tanhl(x).
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 *	2.  0      <= x <= 2**-55 : tanhl(x) := x*(one+x)
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 *					         -t
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 *	    2**-55 <  x <=  1     : tanhl(x) := -----; t = expm1l(-2x)
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 *					        t + 2
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 *						      2
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 *	    1      <= x <=  23.0  : tanhl(x) := 1-  ----- ; t=expm1l(2x)
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 *						    t + 2
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 *	    23.0   <  x <= INF    : tanhl(x) := 1.
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 *
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 * Special cases:
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 *	tanhl(NaN) is NaN;
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 *	only tanhl(0)=0 is exact for finite argument.
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 */
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#include <math.h>
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#include "math_private.h"
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static const long double one=1.0, two=2.0, tiny = 1.0e-4900L;
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long double
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tanhl(long double x)
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{
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	long double t,z;
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	int32_t se;
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	u_int32_t jj0,jj1,ix;
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    /* High word of |x|. */
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	GET_LDOUBLE_WORDS(se,jj0,jj1,x);
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	ix = se&0x7fff;
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    /* x is INF or NaN */
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	if(ix==0x7fff) {
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	    /* for NaN it's not important which branch: tanhl(NaN) = NaN */
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	    if (se&0x8000) return one/x-one;	/* tanhl(-inf)= -1; */
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	    else	   return one/x+one;	/* tanhl(+inf)=+1 */
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	}
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    /* |x| < 23 */
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	if (ix < 0x4003 || (ix == 0x4003 && jj0 < 0xb8000000u)) {/* |x|<23 */
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	    if ((ix|jj0|jj1) == 0)
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		return x;		/* x == +- 0 */
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	    if (ix<0x3fc8)		/* |x|<2**-55 */
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		return x*(one+tiny);	/* tanh(small) = small */
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	    if (ix>=0x3fff) {	/* |x|>=1  */
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		t = expm1l(two*fabsl(x));
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		z = one - two/(t+two);
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	    } else {
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		t = expm1l(-two*fabsl(x));
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		z= -t/(t+two);
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	    }
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    /* |x| > 23, return +-1 */
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	} else {
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	    z = one - tiny;		/* raised inexact flag */
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	}
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	return (se&0x8000)? -z: z;
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}