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 #include "math.h"
17 #include "math_private.h"
18
19 static const float one = 1.0, huge = 1e30;
20
21 static const float zero = 0.0;
22
23 float
atanhf(float x)24 atanhf(float x)
25 {
26 float t;
27 int32_t hx,ix;
28 GET_FLOAT_WORD(hx,x);
29 ix = hx&0x7fffffff;
30 if (ix>0x3f800000) /* |x|>1 */
31 return (x-x)/(x-x);
32 if(ix==0x3f800000)
33 return x/zero;
34 if(ix<0x31800000&&(huge+x)>zero) return x; /* x<2**-28 */
35 SET_FLOAT_WORD(x,ix);
36 if(ix<0x3f000000) { /* x < 0.5 */
37 t = x+x;
38 t = (float)0.5*log1pf(t+t*x/(one-x));
39 } else
40 t = (float)0.5*log1pf((x+x)/(one-x));
41 if(hx>=0) return t; else return -t;
42 }
43