xref: /illumos-gate/usr/src/lib/libm/common/complex/csin.c (revision ddc0e0b5)
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 __csin = csin
31 
32 /* INDENT OFF */
33 /*
34  * dcomplex csin(dcomplex z);
35  *
36  * If z = x+iy, then since csin(iz) = i*csinh(z),  we have
37  *
38  * csin(z)	= csin((-1)*(-z)) = csin(i*i*(-z))
39  *		= i*csinh(i*(-z)) = i*csinh(i*(-x-yi))
40  *		= i*csinh(y-ix)
41  *		= -Im(csinh(y-ix))+i*Re(csinh(y-ix))
42  */
43 /* INDENT ON */
44 
45 #include "libm.h"
46 #include "complex_wrapper.h"
47 
48 dcomplex
csin(dcomplex z)49 csin(dcomplex z) {
50 	double x, y;
51 	dcomplex ans, ct;
52 
53 	x = D_RE(z);
54 	y = D_IM(z);
55 	D_RE(z) = y;
56 	D_IM(z) = -x;
57 	ct = csinh(z);
58 	D_RE(ans) = -D_IM(ct);
59 	D_IM(ans) = D_RE(ct);
60 	return (ans);
61 }
62