/* 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.

 * ====================================================

 */

/* __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 <float.h>

#include <math.h>

#include <math-barriers.h>

#include <math_private.h>

#include <math-underflow.h>

static const long double one = 1.0, huge = 1e4900L;

static const long double zero = 0.0;

long double

__ieee754_atanhl(long double x)

{

	long double t;

	int32_t ix;

	uint32_t se,i0,i1;

	GET_LDOUBLE_WORDS(se,i0,i1,x);

	ix = se&0x7fff;

	if ((ix+((((i0&0x7fffffff)|i1)|(-((i0&0x7fffffff)|i1)))>>31))>0x3fff)

	  /* |x|>1 */

	    return (x-x)/(x-x);

	if(ix==0x3fff)

	    return x/zero;

	if(ix<0x3fdf) {

	    math_force_eval(huge+x);

	    math_check_force_underflow (x);

	    return x;	/* x<2**-32 */

	}

	SET_LDOUBLE_EXP(x,ix);

	if(ix<0x3ffe) {		/* x < 0.5 */

	    t = x+x;

	    t = 0.5*__log1pl(t+t*x/(one-x));

	} else

	    t = 0.5*__log1pl((x+x)/(one-x));

	if(se<=0x7fff) return t; else return -t;

}

strong_alias (__ieee754_atanhl, __atanhl_finite)