xref: /illumos-gate/usr/src/lib/libm/common/C/atan2pi.c (revision ddc0e0b53c661f6e439e3b7072b3ef353eadb4af)
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 /*
30  * atan2pi(x) = atan2(x)/pi
31  */
32 
33 #include "libm.h"
34 
35 static const double invpi = 0.3183098861837906715377675;
36 
37 double
atan2pi(double y,double x)38 atan2pi(double y, double x) {
39 	int	ix, iy;
40 
41 	if (x == 0.0 && y == 0.0) {
42 		ix = ((int *)&x)[HIWORD];
43 		iy = ((int *)&y)[HIWORD];
44 		if (ix >= 0)
45 			return (y);
46 		return ((iy >= 0)? 1.0 : -1.0);
47 	}
48 	return (atan2(y, x) * invpi);
49 }
50