1
/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
3
* ***** BEGIN LICENSE BLOCK *****
4
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
6
* The contents of this file are subject to the Mozilla Public License Version
7
* 1.1 (the "License"); you may not use this file except in compliance with
8
* the License. You may obtain a copy of the License at
9
* http://www.mozilla.org/MPL/
11
* Software distributed under the License is distributed on an "AS IS" basis,
12
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
13
* for the specific language governing rights and limitations under the
16
* The Original Code is Mozilla Communicator client code, released
19
* The Initial Developer of the Original Code is
20
* Sun Microsystems, Inc.
21
* Portions created by the Initial Developer are Copyright (C) 1998
22
* the Initial Developer. All Rights Reserved.
26
* Alternatively, the contents of this file may be used under the terms of
27
* either of the GNU General Public License Version 2 or later (the "GPL"),
28
* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
29
* in which case the provisions of the GPL or the LGPL are applicable instead
30
* of those above. If you wish to allow use of your version of this file only
31
* under the terms of either the GPL or the LGPL, and not to allow others to
32
* use your version of this file under the terms of the MPL, indicate your
33
* decision by deleting the provisions above and replace them with the notice
34
* and other provisions required by the GPL or the LGPL. If you do not delete
35
* the provisions above, a recipient may use your version of this file under
36
* the terms of any one of the MPL, the GPL or the LGPL.
38
* ***** END LICENSE BLOCK ***** */
40
/* @(#)e_atanh.c 1.3 95/01/18 */
42
* ====================================================
43
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
45
* Developed at SunSoft, a Sun Microsystems, Inc. business.
46
* Permission to use, copy, modify, and distribute this
47
* software is freely granted, provided that this notice
49
* ====================================================
55
* 1.Reduced x to positive by atanh(-x) = -atanh(x)
58
* atanh(x) = --- * log(1 + -------) = 0.5 * log1p(2 * --------)
62
* atanh(x) = 0.5*log1p(2x+2x*x/(1-x))
65
* atanh(x) is NaN if |x| > 1 with signal;
66
* atanh(NaN) is that NaN with no signal;
67
* atanh(+-1) is +-INF with signal.
74
static const double one = 1.0, really_big = 1e300;
76
static double one = 1.0, really_big = 1e300;
79
static double zero = 0.0;
82
double __ieee754_atanh(double x)
84
double __ieee754_atanh(x)
93
hx = __HI(u); /* high word */
94
lx = __LO(u); /* low word */
96
if ((ix|((lx|(-(int)lx))>>31))>0x3ff00000) /* |x|>1 */
100
if(ix<0x3e300000&&(really_big+x)>zero) return x; /* x<2**-28 */
102
__HI(u) = ix; /* x <- |x| */
104
if(ix<0x3fe00000) { /* x < 0.5 */
106
t = 0.5*fd_log1p(t+t*x/(one-x));
108
t = 0.5*fd_log1p((x+x)/(one-x));
109
if(hx>=0) return t; else return -t;