/home/jaouen/pok_official/pok/trunk/libpok/libm/asinhf.c

/*
 *                               POK header
 * 
 * The following file is a part of the POK project. Any modification should
 * made according to the POK licence. You CANNOT use this file or a part of
 * this file is this part of a file for your own project
 *
 * For more information on the POK licence, please see our LICENCE FILE
 *
 * Please follow the coding guidelines described in doc/CODING_GUIDELINES
 *
 *                                      Copyright (c) 2007-2009 POK team 
 *
 * Created by julien on Fri Jan 30 14:41:34 2009 
 */

/* s_asinhf.c -- float version of s_asinh.c.
 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@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.
 * ====================================================
 */

#ifdef POK_NEEDS_LIBMATH

#include <types.h>
#include <libm.h>
#include "math_private.h"

static const float
one =  1.0000000000e+00, /* 0x3F800000 */
ln2 =  6.9314718246e-01, /* 0x3f317218 */
huge=  1.0000000000e+30;

float
asinhf(float x)
{
        float t,w;
        int32_t hx,ix;
        GET_FLOAT_WORD(hx,x);
        ix = hx&0x7fffffff;
        if(ix>=0x7f800000) return x+x;  /* x is inf or NaN */
        if(ix< 0x31800000) {    /* |x|<2**-28 */
            if(huge+x>one) return x;    /* return x inexact except 0 */
        }
        if(ix>0x4d800000) {     /* |x| > 2**28 */
            w = __ieee754_logf(fabsf(x))+ln2;
        } else if (ix>0x40000000) {     /* 2**28 > |x| > 2.0 */
            t = fabsf(x);
            w = __ieee754_logf((float)2.0*t+one/(__ieee754_sqrtf(x*x+one)+t));
        } else {                /* 2.0 > |x| > 2**-28 */
            t = x*x;
            w =log1pf(fabsf(x)+t/(one+__ieee754_sqrtf(one+t)));
        }
        if(hx>0) return w; else return -w;
}
#endif