sysdeps/ieee754/flt-32/e_coshf.c

   1 /* e_coshf.c -- float version of e_cosh.c.
   2  * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
   3  * Optimizations by Ulrich Drepper <drepper@gmail.com>, 2011
   4  */
   5
   6 /*
   7  * ====================================================
   8  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   9  *
  10  * Developed at SunPro, a Sun Microsystems, Inc. business.
  11  * Permission to use, copy, modify, and distribute this
  12  * software is freely granted, provided that this notice
  13  * is preserved.
  14  * ====================================================
  15  */
  16
  17 #include "math.h"
  18 #include "math_private.h"
  19
  20 static const float huge = 1.0e30;
  21 static const float one = 1.0, half=0.5;
  22
  23 float
  24 __ieee754_coshf (float x)
  25 {
  26         float t,w;
  27         int32_t ix;
  28
  29         GET_FLOAT_WORD(ix,x);
  30         ix &= 0x7fffffff;
  31
  32     /* |x| in [0,22] */
  33         if (ix < 0x41b00000) {
  34             /* |x| in [0,0.5*ln2], return 1+expm1(|x|)^2/(2*exp(|x|)) */
  35                 if(ix<0x3eb17218) {
  36                     t = __expm1f(fabsf(x));
  37                     w = one+t;
  38                     if (ix<0x24000000) return w;        /* cosh(tiny) = 1 */
  39                     return one+(t*t)/(w+w);
  40                 }
  41
  42             /* |x| in [0.5*ln2,22], return (exp(|x|)+1/exp(|x|)/2; */
  43                 t = __ieee754_expf(fabsf(x));
  44                 return half*t+half/t;
  45         }
  46
  47     /* |x| in [22, log(maxdouble)] return half*exp(|x|) */
  48         if (ix < 0x42b17180)  return half*__ieee754_expf(fabsf(x));
  49
  50     /* |x| in [log(maxdouble), overflowthresold] */
  51         if (ix<=0x42b2d4fc) {
  52             w = __ieee754_expf(half*fabsf(x));
  53             t = half*w;
  54             return t*w;
  55         }
  56
  57     /* x is INF or NaN */
  58         if(ix>=0x7f800000) return x*x;
  59
  60     /* |x| > overflowthresold, cosh(x) overflow */
  61         return huge*huge;
  62 }
  63 strong_alias (__ieee754_coshf, __coshf_finite)