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 <sys/cdefs.h>
17 #if defined(LIBM_SCCS) && !defined(lint)
18 __RCSID("$NetBSD: e_atanhf.c,v 1.7 2002/05/26 22:01:49 wiz Exp $");
19 #endif
20
21 #include "math.h"
22 #include "math_private.h"
23
24 static const float one = 1.0, huge = 1e30;
25
26 static const float zero = 0.0;
27
28 float
__ieee754_atanhf(float x)29 __ieee754_atanhf(float x)
30 {
31 float t;
32 int32_t hx,ix;
33 GET_FLOAT_WORD(hx,x);
34 ix = hx&0x7fffffff;
35 if (ix>0x3f800000) /* |x|>1 */
36 return (x-x)/(x-x);
37 if(ix==0x3f800000)
38 return x/zero;
39 if(ix<0x31800000&&(huge+x)>zero) return x; /* x<2**-28 */
40 SET_FLOAT_WORD(x,ix);
41 if(ix<0x3f000000) { /* x < 0.5 */
42 t = x+x;
43 t = (float)0.5*log1pf(t+t*x/(one-x));
44 } else
45 t = (float)0.5*log1pf((x+x)/(one-x));
46 if(hx>=0) return t; else return -t;
47 }
48