xref: /titanic_51/usr/src/lib/libm/common/LD/acoshl.c (revision 25c28e83beb90e7c80452a7c818c5e6f73a07dc8)
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 #if defined(ELFOBJ)
31 #pragma weak acoshl = __acoshl
32 #endif
33 
34 #include "libm.h"
35 
36 static const long double
37 	zero	= 0.0L,
38 	ln2	= 6.931471805599453094172321214581765680755e-0001L,
39 	one	= 1.0L,
40 	big	= 1.e+20L;
41 
42 long double
43 acoshl(long double x) {
44 	long double t;
45 
46 	if (isnanl(x))
47 		return (x + x);
48 	else if (x > big)
49 		return (logl(x) + ln2);
50 	else if (x > one) {
51 		t = sqrtl(x - one);
52 		return (log1pl(t * (t + sqrtl(x + one))));
53 	} else if (x == one)
54 		return (zero);
55 	else
56 		return ((x - x) / (x - x));
57 }
58