newlib/libm/math/sf_asinh.c

   1 /* sf_asinh.c -- float version of s_asinh.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
  20 #else
  21 static float
  22 #endif
  23 one =  1.0000000000e+00, /* 0x3F800000 */
  24 ln2 =  6.9314718246e-01, /* 0x3f317218 */
  25 huge=  1.0000000000e+30;
  26
  27 #ifdef __STDC__
  28         float asinhf(float x)
  29 #else
  30         float asinhf(x)
  31         float x;
  32 #endif
  33 {
  34         float t,w;
  35         __int32_t hx,ix;
  36         GET_FLOAT_WORD(hx,x);
  37         ix = hx&0x7fffffff;
  38         if(!FLT_UWORD_IS_FINITE(ix)) return x+x;        /* x is inf or NaN */
  39         if(ix< 0x31800000) {    /* |x|<2**-28 */
  40             if(huge+x>one) return x;    /* return x inexact except 0 */
  41         }
  42         if(ix>0x4d800000) {     /* |x| > 2**28 */
  43             w = __ieee754_logf(fabsf(x))+ln2;
  44         } else if (ix>0x40000000) {     /* 2**28 > |x| > 2.0 */
  45             t = fabsf(x);
  46             w = __ieee754_logf((float)2.0*t+one/(__ieee754_sqrtf(x*x+one)+t));
  47         } else {                /* 2.0 > |x| > 2**-28 */
  48             t = x*x;
  49             w =log1pf(fabsf(x)+t/(one+__ieee754_sqrtf(one+t)));
  50         }
  51         if(hx>0) return w; else return -w;
  52 }
  53
  54 #ifdef _DOUBLE_IS_32BITS
  55
  56 #ifdef __STDC__
  57         double asinh(double x)
  58 #else
  59         double asinh(x)
  60         double x;
  61 #endif
  62 {
  63         return (double) asinhf((float) x);
  64 }
  65
  66 #endif /* defined(_DOUBLE_IS_32BITS) */