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[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.17.0/] [newlib/] [libm/] [math/] [e_sinh.c] - Blame information for rev 148

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1 148 jeremybenn 
 
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/* @(#)e_sinh.c 5.1 93/09/24 */
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/*
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 * ====================================================
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 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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 *
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 * Developed at SunPro, a Sun Microsystems, Inc. business.
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 * Permission to use, copy, modify, and distribute this
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 * software is freely granted, provided that this notice
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 * is preserved.
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 * ====================================================
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 */
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/* __ieee754_sinh(x)
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 * Method :
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 * mathematically sinh(x) if defined to be (exp(x)-exp(-x))/2
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 *      1. Replace x by |x| (sinh(-x) = -sinh(x)).
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 *      2.
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 *                                                  E + E/(E+1)
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 *          0        <= x <= 22     :  sinh(x) := --------------, E=expm1(x)
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 *                                                      2
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 *
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 *          22       <= x <= lnovft :  sinh(x) := exp(x)/2
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 *          lnovft   <= x <= ln2ovft:  sinh(x) := exp(x/2)/2 * exp(x/2)
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 *          ln2ovft  <  x           :  sinh(x) := x*shuge (overflow)
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 *
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 * Special cases:
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 *      sinh(x) is |x| if x is +INF, -INF, or NaN.
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 *      only sinh(0)=0 is exact for finite x.
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 */
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#include "fdlibm.h"
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#ifndef _DOUBLE_IS_32BITS
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#ifdef __STDC__
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static const double one = 1.0, shuge = 1.0e307;
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#else
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static double one = 1.0, shuge = 1.0e307;
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#endif
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#ifdef __STDC__
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        double __ieee754_sinh(double x)
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#else
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        double __ieee754_sinh(x)
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        double x;
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#endif
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{
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        double t,w,h;
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        __int32_t ix,jx;
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        __uint32_t lx;
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    /* High word of |x|. */
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        GET_HIGH_WORD(jx,x);
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        ix = jx&0x7fffffff;
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    /* x is INF or NaN */
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        if(ix>=0x7ff00000) return x+x;
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        h = 0.5;
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        if (jx<0) h = -h;
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    /* |x| in [0,22], return sign(x)*0.5*(E+E/(E+1))) */
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        if (ix < 0x40360000) {          /* |x|<22 */
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            if (ix<0x3e300000)          /* |x|<2**-28 */
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                if(shuge+x>one) return x;/* sinh(tiny) = tiny with inexact */
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            t = expm1(fabs(x));
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            if(ix<0x3ff00000) return h*(2.0*t-t*t/(t+one));
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            return h*(t+t/(t+one));
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        }
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    /* |x| in [22, log(maxdouble)] return 0.5*exp(|x|) */
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        if (ix < 0x40862E42)  return h*__ieee754_exp(fabs(x));
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    /* |x| in [log(maxdouble), overflowthresold] */
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        GET_LOW_WORD(lx,x);
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       if (ix<0x408633CE || (ix==0x408633ce && lx<=(__uint32_t)0x8fb9f87d)) {
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            w = __ieee754_exp(0.5*fabs(x));
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            t = h*w;
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            return t*w;
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        }
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    /* |x| > overflowthresold, sinh(x) overflow */
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        return x*shuge;
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}
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#endif /* defined(_DOUBLE_IS_32BITS) */

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