(__ieee754_sqrt): Remove unused variables b and n.
[kopensolaris-gnu/glibc.git] / sysdeps / ieee754 / ldbl-96 / e_atanhl.c
1 /* s_atanhl.c -- long double version of s_atan.c.
2  * Conversion to long double by Ulrich Drepper,
3  * Cygnus Support, drepper@cygnus.com.
4  */
5
6 /*
7  * ====================================================
8  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
9  *
10  * Developed at SunPro, a Sun Microsystems, Inc. business.
11  * Permission to use, copy, modify, and distribute this
12  * software is freely granted, provided that this notice
13  * is preserved.
14  * ====================================================
15  */
16
17 #if defined(LIBM_SCCS) && !defined(lint)
18 static char rcsid[] = "$NetBSD: $";
19 #endif
20
21 /* __ieee754_atanhl(x)
22  * Method :
23  *    1.Reduced x to positive by atanh(-x) = -atanh(x)
24  *    2.For x>=0.5
25  *                   1              2x                          x
26  *      atanhl(x) = --- * log(1 + -------) = 0.5 * log1p(2 * --------)
27  *                   2             1 - x                      1 - x
28  *
29  *      For x<0.5
30  *      atanhl(x) = 0.5*log1pl(2x+2x*x/(1-x))
31  *
32  * Special cases:
33  *      atanhl(x) is NaN if |x| > 1 with signal;
34  *      atanhl(NaN) is that NaN with no signal;
35  *      atanhl(+-1) is +-INF with signal.
36  *
37  */
38
39 #include "math.h"
40 #include "math_private.h"
41
42 #ifdef __STDC__
43 static const long double one = 1.0, huge = 1e4900L;
44 #else
45 static long double one = 1.0, huge = 1e4900L;
46 #endif
47
48 #ifdef __STDC__
49 static const long double zero = 0.0;
50 #else
51 static double long zero = 0.0;
52 #endif
53
54 #ifdef __STDC__
55         long double __ieee754_atanhl(long double x)
56 #else
57         long double __ieee754_atanhl(x)
58         long double x;
59 #endif
60 {
61         long double t;
62         int32_t ix;
63         u_int32_t se,i0,i1;
64         GET_LDOUBLE_WORDS(se,i0,i1,x);
65         ix = se&0x7fff;
66         if ((ix+((((i0&0x7fffffff)|i1)|(-((i0&0x7fffffff)|i1)))>>31))>0x3fff)
67           /* |x|>1 */
68             return (x-x)/(x-x);
69         if(ix==0x3fff)
70             return x/zero;
71         if(ix<0x3fe3&&(huge+x)>zero) return x;  /* x<2**-28 */
72         SET_LDOUBLE_EXP(x,ix);
73         if(ix<0x3ffe) {         /* x < 0.5 */
74             t = x+x;
75             t = 0.5*__log1pl(t+t*x/(one-x));
76         } else
77             t = 0.5*__log1pl((x+x)/(one-x));
78         if(se<=0x7fff) return t; else return -t;
79 }