/*--------------------------------------------------------------------

 *© Portions copyright (c) 2006 Nokia Corporation.  All rights reserved.

 *--------------------------------------------------------------------

*/

/* @(#)s_asinh.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.

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

 */

#ifndef __SYMBIAN32__

#ifndef lint

static char rcsid[] = "$FreeBSD: src/lib/msun/src/s_asinh.c,v 1.8 2002/05/28 18:15:04 alfred Exp $";

#endif

#endif //__SYMBIAN32__

/* asinh(x)

 * Method :

 *	Based on

 *		asinh(x) = sign(x) * log [ |x| + sqrt(x*x+1) ]

 *	we have

 *	asinh(x) := x  if  1+x*x=1,

 *		 := sign(x)*(log(x)+ln2)) for large |x|, else

 *		 := sign(x)*log(2|x|+1/(|x|+sqrt(x*x+1))) if|x|>2, else

 *		 := sign(x)*log1p(|x| + x^2/(1 + sqrt(1+x^2)))

 */

#include <math.h>

#include "math_private.h"

static const double

one =  1.00000000000000000000e+00, /* 0x3FF00000, 0x00000000 */

ln2 =  6.93147180559945286227e-01, /* 0x3FE62E42, 0xFEFA39EF */

huge=  1.00000000000000000000e+300;

EXPORT_C double

asinh(double x)

{

	double t,w;

	int32_t hx,ix;

	GET_HIGH_WORD(hx,x);

	ix = hx&0x7fffffff;

	if(ix>=0x7ff00000) return x+x;	/* x is inf or NaN */

	if(ix< 0x3e300000) {	/* |x|<2**-28 */

	    if(huge+x>one) return x;	/* return x inexact except 0 */

	}

	if(ix>0x41b00000) {	/* |x| > 2**28 */

	    w = __ieee754_log(fabs(x))+ln2;

	} else if (ix>0x40000000) {	/* 2**28 > |x| > 2.0 */

	    t = fabs(x);

	    w = __ieee754_log(2.0*t+one/(__ieee754_sqrt(x*x+one)+t));

	} else {		/* 2.0 > |x| > 2**-28 */

	    t = x*x;

	    w =log1p(fabs(x)+t/(one+__ieee754_sqrt(one+t)));

	}

	if(hx>0) return w; else return -w;

}