e_sinhf.c

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

#include "math.h"
#include "math_private.h"

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

float
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*expf(fabsf(x));

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

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