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#if defined(LIBM_SCCS) && !defined(lint)
17static char rcsid[] = "$NetBSD: e_atanhf.c,v 1.4 1995/05/10 20:44:56 jtc Exp $";
18#endif
19
20#include "math.h"
21#include "math_private.h"
22
23#ifdef __STDC__
24static const float one = 1.0, huge = 1e30;
25#else
26static float one = 1.0, huge = 1e30;
27#endif
28
29#ifdef __STDC__
30static const float zero = 0.0;
31#else
32static float zero = 0.0;
33#endif
34
35#ifdef __STDC__
36	float __ieee754_atanhf(float x)
37#else
38	float __ieee754_atanhf(x)
39	float x;
40#endif
41{
42	float t;
43	int32_t hx,ix;
44	GET_FLOAT_WORD(hx,x);
45	ix = hx&0x7fffffff;
46	if (ix>0x3f800000) 		/* |x|>1 */
47	    return (x-x)/(x-x);
48	if(ix==0x3f800000)
49	    return x/zero;
50	if(ix<0x31800000&&(huge+x)>zero) return x;	/* x<2**-28 */
51	SET_FLOAT_WORD(x,ix);
52	if(ix<0x3f000000) {		/* x < 0.5 */
53	    t = x+x;
54	    t = (float)0.5*__log1pf(t+t*x/(one-x));
55	} else
56	    t = (float)0.5*__log1pf((x+x)/(one-x));
57	if(hx>=0) return t; else return -t;
58}
59