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
__ieee754_atanhf(float x)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 }
47