compiler/mlib/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 #ifndef lint
  17 static char rcsid[] = "$FreeBSD: src/lib/msun/src/e_atanhf.c,v 1.6 2002/05/28 17:03:12 alfred Exp $";
  18 #endif
  19
  20 #include "math.h"
  21 #include "math_private.h"
  22
  23 static const float one = 1.0, huge = 1e30;
  24
  25 static const float zero = 0.0;
  26
  27 float
  28 __ieee754_atanhf(float x)
  29 {
  30         float t;
  31         int32_t hx,ix;
  32         GET_FLOAT_WORD(hx,x);
  33         ix = hx&0x7fffffff;
  34         if (ix>0x3f800000)              /* |x|>1 */
  35             return (x-x)/(x-x);
  36         if(ix==0x3f800000)
  37             return x/zero;
  38         if(ix<0x31800000&&(huge+x)>zero) return x;      /* x<2**-28 */
  39         SET_FLOAT_WORD(x,ix);
  40         if(ix<0x3f000000) {             /* x < 0.5 */
  41             t = x+x;
  42             t = (float)0.5*log1pf(t+t*x/(one-x));
  43         } else
  44             t = (float)0.5*log1pf((x+x)/(one-x));
  45         if(hx>=0) return t; else return -t;
  46 }