xref: /titanic_51/usr/src/lib/libm/common/LD/acoshl.c (revision 1ec68d336ba97cd53f46053ac10401d16014d075)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 
22 /*
23  * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
24  */
25 /*
26  * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
27  * Use is subject to license terms.
28  */
29 
30 #pragma weak acoshl = __acoshl
31 
32 #include "libm.h"
33 
34 static const long double
35 	zero	= 0.0L,
36 	ln2	= 6.931471805599453094172321214581765680755e-0001L,
37 	one	= 1.0L,
38 	big	= 1.e+20L;
39 
40 long double
41 acoshl(long double x) {
42 	long double t;
43 
44 	if (isnanl(x))
45 		return (x + x);
46 	else if (x > big)
47 		return (logl(x) + ln2);
48 	else if (x > one) {
49 		t = sqrtl(x - one);
50 		return (log1pl(t * (t + sqrtl(x + one))));
51 	} else if (x == one)
52 		return (zero);
53 	else
54 		return ((x - x) / (x - x));
55 }
56