s_asinhf.c

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/* 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.
 * ====================================================
 */

#include "math.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 = logf(fabsf(x))+ln2;
    } else if (ix>0x40000000) { /* 2**28 > |x| > 2.0 */
        t = fabsf(x);
        w = logf((float)2.0*t+one/(sqrtf(x*x+one)+t));
    } else {        /* 2.0 > |x| > 2**-28 */
        t = x*x;
        w =log1pf(fabsf(x)+t/(one+sqrtf(one+t)));
    }
    if(hx>0) return w; else return -w;
}