usr/src/lib/libm/common/complex/carg.c

   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 }