xref: /illumos-gate/usr/src/lib/libm/common/complex/carg.c (revision c5bab7026b8e0ac44b25ee08507ea360f177d844)
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 __carg = carg
30 
31 #include <math.h>		/* atan2 */
32 #include "complex_wrapper.h"
33 
34 static const double
35 	pi	= 3.14159265358979311600e+00,
36 	pi_lo	= 1.22464679914735320717e-16;
37 
38 double
39 carg(dcomplex z) {
40 	int	ix, iy;
41 
42 	ix = ((int *)&(D_RE(z)))[HIWORD];
43 	iy = ((int *)&(D_IM(z)))[HIWORD];
44 	if ((((ix | iy) & ~0x80000000) | ((int *)&(D_RE(z)))[LOWORD] |
45 	    ((int *)&(D_IM(z)))[LOWORD]) == 0) {
46 		/* x and y are both zero */
47 		if (ix == 0)
48 			return (D_IM(z));
49 		return ((iy == 0)? pi + pi_lo : -pi - pi_lo);
50 	}
51 	return (atan2(D_IM(z), D_RE(z)));
52 }
53