/home/jaouen/pok_official/pok/trunk/libpok/libm/e_sinhf.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 
 */

/* e_sinhf.c -- float version of e_sinh.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 <libm.h>
#include "math_private.h"

static const float one = 1.0, shuge = 1.0e37;

float
__ieee754_sinhf(float x)
{
        float t,w,h;
        int32_t ix,jx;

        GET_FLOAT_WORD(jx,x);
        ix = jx&0x7fffffff;

    /* x is INF or NaN */
        if(ix>=0x7f800000) return x+x;

        h = 0.5;
        if (jx<0) h = -h;
    /* |x| in [0,22], return sign(x)*0.5*(E+E/(E+1))) */
        if (ix < 0x41b00000) {          /* |x|<22 */
            if (ix<0x31800000)          /* |x|<2**-28 */
                if(shuge+x>one) return x;/* sinh(tiny) = tiny with inexact */
            t = expm1f(fabsf(x));
            if(ix<0x3f800000) return h*((float)2.0*t-t*t/(t+one));
            return h*(t+t/(t+one));
        }

    /* |x| in [22, log(maxdouble)] return 0.5*exp(|x|) */
        if (ix < 0x42b17180)  return h*__ieee754_expf(fabsf(x));

    /* |x| in [log(maxdouble), overflowthresold] */
        if (ix<=0x42b2d4fc) {
            w = __ieee754_expf((float)0.5*fabsf(x));
            t = h*w;
            return t*w;
        }

    /* |x| > overflowthresold, sinh(x) overflow */
        return x*shuge;
}
#endif