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/* @(#)e_sinh.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.

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

 */

#if defined(LIBM_SCCS) && !defined(lint)

static char rcsid[] = "$NetBSD: e_sinh.c,v 1.7 1995/05/10 20:46:13 jtc Exp $";

#endif

/* __ieee754_sinh(x)

 * Method :

 * mathematically sinh(x) if defined to be (exp(x)-exp(-x))/2

 *      1. Replace x by |x| (sinh(-x) = -sinh(x)).

 *      2.

 *                                                  E + E/(E+1)

 *          0        <= x <= 22     :  sinh(x) := --------------, E=expm1(x)

 *                                                      2

 *

 *          22       <= x <= lnovft :  sinh(x) := exp(x)/2

 *          lnovft   <= x <= ln2ovft:  sinh(x) := exp(x/2)/2 * exp(x/2)

 *          ln2ovft  <  x           :  sinh(x) := x*shuge (overflow)

 *

 * Special cases:

 *      sinh(x) is |x| if x is +INF, -INF, or NaN.

 *      only sinh(0)=0 is exact for finite x.

 */

#include "math.h"

#include "math_private.h"

#ifdef __STDC__

static const double one = 1.0, shuge = 1.0e307;

#else

static double one = 1.0, shuge = 1.0e307;

#endif

#ifdef __STDC__

        double __ieee754_sinh(double x)

#else

        double __ieee754_sinh(x)

        double x;

#endif

{

        double t,w,h;

        int32_t ix,jx;

        u_int32_t lx;

    /* High word of |x|. */

        GET_HIGH_WORD(jx,x);

        ix = jx&0x7fffffff;

    /* x is INF or NaN */

        if(ix>=0x7ff00000) 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 < 0x40360000) {          /* |x|<22 */

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

                if(shuge+x>one) return x;/* sinh(tiny) = tiny with inexact */

            t = expm1(fabs(x));

            if(ix<0x3ff00000) return h*(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 < 0x40862E42)  return h*__ieee754_exp(fabs(x));

    /* |x| in [log(maxdouble), overflowthresold] */

        GET_LOW_WORD(lx,x);

        if (ix<0x408633CE || ((ix==0x408633ce)&&(lx<=(u_int32_t)0x8fb9f87d))) {

            w = __ieee754_exp(0.5*fabs(x));

            t = h*w;

            return t*w;

        }

    /* |x| > overflowthresold, sinh(x) overflow */

        return x*shuge;

}