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
  16 #include <sys/cdefs.h>
  17 #if defined(LIBM_SCCS) && !defined(lint)
  18 __RCSID("$NetBSD: e_sinhf.c,v 1.7 2002/05/26 22:01:52 wiz Exp $");
  19 #endif
  20
  21 #include "math.h"
  22 #include "math_private.h"
  23
  24 static const float one = 1.0, shuge = 1.0e37;
  25
  26 float
  27 __ieee754_sinhf(float x)
  28 {
  29         float t,w,h;
  30         int32_t ix,jx;
  31
  32         GET_FLOAT_WORD(jx,x);
  33         ix = jx&0x7fffffff;
  34
  35     /* x is INF or NaN */
  36         if(ix>=0x7f800000) return x+x;
  37
  38         h = 0.5;
  39         if (jx<0) h = -h;
  40     /* |x| in [0,22], return sign(x)*0.5*(E+E/(E+1))) */
  41         if (ix < 0x41b00000) {          /* |x|<22 */
  42             if (ix<0x31800000)          /* |x|<2**-28 */
  43                 if(shuge+x>one) return x;/* sinh(tiny) = tiny with inexact */
  44             t = expm1f(fabsf(x));
  45             if(ix<0x3f800000) return h*((float)2.0*t-t*t/(t+one));
  46             return h*(t+t/(t+one));
  47         }
  48
  49     /* |x| in [22, log(maxdouble)] return 0.5*exp(|x|) */
  50         if (ix < 0x42b17180)  return h*__ieee754_expf(fabsf(x));
  51
  52     /* |x| in [log(maxdouble), overflowthresold] */
  53         if (ix<=0x42b2d4fc) {
  54             w = __ieee754_expf((float)0.5*fabsf(x));
  55             t = h*w;
  56             return t*w;
  57         }
  58
  59     /* |x| > overflowthresold, sinh(x) overflow */
  60         return x*shuge;
  61 }