Standard Libraries for EDK II.

[mirror_edk2.git] / StdLib / LibC / Math / e_sinh.c

/* @(#)e_sinh.c 5.1 93/09/24 */\r
/*\r
 * ====================================================\r
 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.\r
 *\r
 * Developed at SunPro, a Sun Microsystems, Inc. business.\r
 * Permission to use, copy, modify, and distribute this\r
 * software is freely granted, provided that this notice\r
 * is preserved.\r
 * ====================================================\r
 */\r
#include  <LibConfig.h>\r
#include  <sys/EfiCdefs.h>\r
#if defined(LIBM_SCCS) && !defined(lint)\r
__RCSID("$NetBSD: e_sinh.c,v 1.11 2002/05/26 22:01:52 wiz Exp $");\r
#endif\r
\r
#include "math.h"\r
#include "math_private.h"\r
\r
/* __ieee754_sinh(x)\r
 * Method :\r
 * mathematically sinh(x) if defined to be (exp(x)-exp(-x))/2\r
 *  1. Replace x by |x| (sinh(-x) = -sinh(x)).\r
 *  2.\r
 *                                        E + E/(E+1)\r
 *      0        <= x <= 22     :  sinh(x) := --------------, E=expm1(x)\r
 *                          2\r
 *\r
 *      22       <= x <= lnovft :  sinh(x) := exp(x)/2\r
 *      lnovft   <= x <= ln2ovft:  sinh(x) := exp(x/2)/2 * exp(x/2)\r
 *      ln2ovft  <  x     :  sinh(x) := x*shuge (overflow)\r
 *\r
 * Special cases:\r
 *  sinh(x) is |x| if x is +INF, -INF, or NaN.\r
 *  only sinh(0)=0 is exact for finite x.\r
 */\r
\r
static const double one = 1.0, shuge = 1.0e307;\r
\r
double\r
__ieee754_sinh(double x)\r
{\r
  double t,w,h;\r
  int32_t ix,jx;\r
  u_int32_t lx;\r
\r
    /* High word of |x|. */\r
  GET_HIGH_WORD(jx,x);\r
  ix = jx&0x7fffffff;\r
\r
    /* x is INF or NaN */\r
  if(ix>=0x7ff00000) return x+x;\r
\r
  h = 0.5;\r
  if (jx<0) h = -h;\r
    /* |x| in [0,22], return sign(x)*0.5*(E+E/(E+1))) */\r
  if (ix < 0x40360000) {    /* |x|<22 */\r
      if (ix<0x3e300000)    /* |x|<2**-28 */\r
    if(shuge+x>one) return x;/* sinh(tiny) = tiny with inexact */\r
      t = expm1(fabs(x));\r
      if(ix<0x3ff00000) return h*(2.0*t-t*t/(t+one));\r
      return h*(t+t/(t+one));\r
  }\r
\r
    /* |x| in [22, log(maxdouble)] return 0.5*exp(|x|) */\r
  if (ix < 0x40862E42)  return h*__ieee754_exp(fabs(x));\r
\r
    /* |x| in [log(maxdouble), overflowthresold] */\r
  GET_LOW_WORD(lx,x);\r
  if (ix<0x408633CE || ((ix==0x408633ce)&&(lx<=(u_int32_t)0x8fb9f87d))) {\r
      w = __ieee754_exp(0.5*fabs(x));\r
      t = h*w;\r
      return t*w;\r
  }\r
\r
    /* |x| > overflowthresold, sinh(x) overflow */\r
  return x*shuge;\r
}\r