sysdeps/ieee754/flt-32/e_atanhf.c

   1 /* e_atanhf.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 #if defined(LIBM_SCCS) && !defined(lint)
  17 static char rcsid[] = "$NetBSD: e_atanhf.c,v 1.4 1995/05/10 20:44:56 jtc Exp $";
  18 #endif
  19
  20 #include "math.h"
  21 #include "math_private.h"
  22
  23 #ifdef __STDC__
  24 static const float one = 1.0, huge = 1e30;
  25 #else
  26 static float one = 1.0, huge = 1e30;
  27 #endif
  28
  29 #ifdef __STDC__
  30 static const float zero = 0.0;
  31 #else
  32 static float zero = 0.0;
  33 #endif
  34
  35 #ifdef __STDC__
  36         float __ieee754_atanhf(float x)
  37 #else
  38         float __ieee754_atanhf(x)
  39         float x;
  40 #endif
  41 {
  42         float t;
  43         int32_t hx,ix;
  44         GET_FLOAT_WORD(hx,x);
  45         ix = hx&0x7fffffff;
  46         if (ix>0x3f800000)              /* |x|>1 */
  47             return (x-x)/(x-x);
  48         if(ix==0x3f800000)
  49             return x/zero;
  50         if(ix<0x31800000&&(huge+x)>zero) return x;      /* x<2**-28 */
  51         SET_FLOAT_WORD(x,ix);
  52         if(ix<0x3f000000) {             /* x < 0.5 */
  53             t = x+x;
  54             t = (float)0.5*__log1pf(t+t*x/(one-x));
  55         } else
  56             t = (float)0.5*__log1pf((x+x)/(one-x));
  57         if(hx>=0) return t; else return -t;
  58 }