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  1. /* ef_sinh.c -- float version of e_sinh.c.
  2.  * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
  3.  */
  4.  
  5. /*
  6.  * ====================================================
  7.  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
  8.  *
  9.  * Developed at SunPro, a Sun Microsystems, Inc. business.
  10.  * Permission to use, copy, modify, and distribute this
  11.  * software is freely granted, provided that this notice
  12.  * is preserved.
  13.  * ====================================================
  14.  */
  15.  
  16. #include "fdlibm.h"
  17.  
  18. #ifdef __STDC__
  19. static const float one = 1.0, shuge = 1.0e37;
  20. #else
  21. static float one = 1.0, shuge = 1.0e37;
  22. #endif
  23.  
  24. #ifdef __STDC__
  25.         float __ieee754_sinhf(float x)
  26. #else
  27.         float __ieee754_sinhf(x)
  28.         float x;
  29. #endif
  30. {      
  31.         float t,w,h;
  32.         __int32_t ix,jx;
  33.  
  34.         GET_FLOAT_WORD(jx,x);
  35.         ix = jx&0x7fffffff;
  36.  
  37.     /* x is INF or NaN */
  38.         if(!FLT_UWORD_IS_FINITE(ix)) return x+x;       
  39.  
  40.         h = 0.5;
  41.         if (jx<0) h = -h;
  42.     /* |x| in [0,22], return sign(x)*0.5*(E+E/(E+1))) */
  43.         if (ix < 0x41b00000) {          /* |x|<22 */
  44.             if (ix<0x31800000)          /* |x|<2**-28 */
  45.                 if(shuge+x>one) return x;/* sinh(tiny) = tiny with inexact */
  46.             t = expm1f(fabsf(x));
  47.             if(ix<0x3f800000) return h*((float)2.0*t-t*t/(t+one));
  48.             return h*(t+t/(t+one));
  49.         }
  50.  
  51.     /* |x| in [22, log(maxdouble)] return 0.5*exp(|x|) */
  52.         if (ix<=FLT_UWORD_LOG_MAX)  return h*__ieee754_expf(fabsf(x));
  53.  
  54.     /* |x| in [log(maxdouble), overflowthresold] */
  55.         if (ix<=FLT_UWORD_LOG_2MAX) {
  56.             w = __ieee754_expf((float)0.5*fabsf(x));
  57.             t = h*w;
  58.             return t*w;
  59.         }
  60.  
  61.     /* |x| > overflowthresold, sinh(x) overflow */
  62.         return x*shuge;
  63. }
  64.