common/complex/carg.c

	carg.c revision 25c28e83beb90e7c80452a7c818c5e6f73a07dc8
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
 */
/*
 * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma weak carg = __carg

#include "libm_synonyms.h"
#include <math.h>       /* atan2 */
#include "complex_wrapper.h"

static const double
    pi  = 3.14159265358979311600e+00,
    pi_lo   = 1.22464679914735320717e-16;

double
carg(dcomplex z) {
    int ix, iy;

    ix = ((int *)&(D_RE(z)))[HIWORD];
    iy = ((int *)&(D_IM(z)))[HIWORD];
    if ((((ix | iy) & ~0x80000000) | ((int *)&(D_RE(z)))[LOWORD] |
        ((int *)&(D_IM(z)))[LOWORD]) == 0) {
        /* x and y are both zero */
        if (ix == 0)
            return (D_IM(z));
        return ((iy == 0)? pi + pi_lo : -pi - pi_lo);
    }
    return (atan2(D_IM(z), D_RE(z)));
}