xref: /illumos-gate/usr/src/lib/libm/common/C/atan2pi.c (revision a6bde1a23b60f140c7ed78df979c2e22b1ed9b2c)
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  * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
23  */
24 /*
25  * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
26  * Use is subject to license terms.
27  */
28 
29 #pragma weak atan2pi = __atan2pi
30 
31 /*
32  * atan2pi(x) = atan2(x)/pi
33  */
34 
35 #include "libm.h"
36 
37 static const double invpi = 0.3183098861837906715377675;
38 
39 double
40 atan2pi(double y, double x) {
41 	int	ix, iy;
42 
43 	if (x == 0.0 && y == 0.0) {
44 		ix = ((int *)&x)[HIWORD];
45 		iy = ((int *)&y)[HIWORD];
46 		if (ix >= 0)
47 			return (y);
48 		return ((iy >= 0)? 1.0 : -1.0);
49 	}
50 	return (atan2(y, x) * invpi);
51 }
52