lib/libm/src/e_sinhf.c

   1 /* e_sinhf.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  * $NetBSD: e_sinhf.c,v 1.7 2002/05/26 22:01:52 wiz Exp $
  16  * $DragonFly: src/lib/libm/src/e_sinhf.c,v 1.1 2005/07/26 21:15:20 joerg Exp $
  17  */
  18
  19 #include <math.h>
  20 #include "math_private.h"
  21
  22 static const float one = 1.0, shuge = 1.0e37;
  23
  24 float
  25 sinhf(float x)
  26 {
  27         float t,w,h;
  28         int32_t ix,jx;
  29
  30         GET_FLOAT_WORD(jx,x);
  31         ix = jx&0x7fffffff;
  32
  33     /* x is INF or NaN */
  34         if(ix>=0x7f800000) return x+x;
  35
  36         h = 0.5;
  37         if (jx<0) h = -h;
  38     /* |x| in [0,22], return sign(x)*0.5*(E+E/(E+1))) */
  39         if (ix < 0x41b00000) {          /* |x|<22 */
  40             if (ix<0x31800000)          /* |x|<2**-28 */
  41                 if(shuge+x>one) return x;/* sinh(tiny) = tiny with inexact */
  42             t = expm1f(fabsf(x));
  43             if(ix<0x3f800000) return h*((float)2.0*t-t*t/(t+one));
  44             return h*(t+t/(t+one));
  45         }
  46
  47     /* |x| in [22, log(maxdouble)] return 0.5*exp(|x|) */
  48         if (ix < 0x42b17180)  return h*expf(fabsf(x));
  49
  50     /* |x| in [log(maxdouble), overflowthresold] */
  51         if (ix<=0x42b2d4fc) {
  52             w = expf((float)0.5*fabsf(x));
  53             t = h*w;
  54             return t*w;
  55         }
  56
  57     /* |x| > overflowthresold, sinh(x) overflow */
  58         return x*shuge;
  59 }