source: trunk/libs/newlib/src/newlib/libm/math/ef_sinh.c @ 567

/* ef_sinh.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 "fdlibm.h"

#ifdef __STDC__
static const float one = 1.0, shuge = 1.0e37;
#else
static float one = 1.0, shuge = 1.0e37;
#endif

#ifdef __STDC__
        float __ieee754_sinhf(float x)
#else
        float __ieee754_sinhf(x)
        float x;
#endif
{       
        float t,w,h;
        __int32_t ix,jx;

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

    /* x is INF or NaN */
        if(!FLT_UWORD_IS_FINITE(ix)) 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<=FLT_UWORD_LOG_MAX)  return h*__ieee754_expf(fabsf(x));

    /* |x| in [log(maxdouble), overflowthresold] */
        if (ix<=FLT_UWORD_LOG_2MAX) {
            w = __ieee754_expf((float)0.5*fabsf(x));
            t = h*w;
            return t*w;
        }

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