toolchain/gcc/newlib/libm/math/ef_atanh.c

   1 /* ef_atanh.c -- float version of e_atanh.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
  17 #include "fdlibm.h"
  18
  19 #ifdef __STDC__
  20 static const float one = 1.0, huge = 1e30;
  21 #else
  22 static float one = 1.0, huge = 1e30;
  23 #endif
  24
  25 #ifdef __STDC__
  26 static const float zero = 0.0;
  27 #else
  28 static float zero = 0.0;
  29 #endif
  30
  31 #ifdef __STDC__
  32         float __ieee754_atanhf(float x)
  33 #else
  34         float __ieee754_atanhf(x)
  35         float x;
  36 #endif
  37 {
  38         float t;
  39         __int32_t hx,ix;
  40         GET_FLOAT_WORD(hx,x);
  41         ix = hx&0x7fffffff;
  42         if (ix>0x3f800000)              /* |x|>1 */
  43             return (x-x)/(x-x);
  44         if(ix==0x3f800000)
  45             return x/zero;
  46         if(ix<0x31800000&&(huge+x)>zero) return x;      /* x<2**-28 */
  47         SET_FLOAT_WORD(x,ix);
  48         if(ix<0x3f000000) {             /* x < 0.5 */
  49             t = x+x;
  50             t = (float)0.5*log1pf(t+t*x/(one-x));
  51         } else
  52             t = (float)0.5*log1pf((x+x)/(one-x));
  53         if(hx>=0) return t; else return -t;
  54 }