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 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 __math_invalidf(x);
32 if (ix == 0x3f800000)
33 return __math_divzerof(x < 0);
34 if (ix < 0x31800000 && (huge + x) > zero)
35 return x; /* x<2**-28 */
36 SET_FLOAT_WORD(x, ix);
37 if (ix < 0x3f000000) { /* x < 0.5 */
38 t = x + x;
39 t = (float)0.5 * log1pf(t + t * x / (one - x));
40 } else
41 t = (float)0.5 * log1pf((x + x) / (one - x));
42 if (hx >= 0)
43 return t;
44 else
45 return -t;
46 }
47
48 _MATH_ALIAS_f_f(atanh)
49
