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 catan = __catan
  31 
  32 /* INDENT OFF */
  33 /*
  34  * dcomplex catan(dcomplex z);
  35  *
  36  * If
  37  *     z = x + iy,
  38  *
  39  * then
  40  *          1       (    2x     )    1                2    2
  41  * Re w  =  - arctan(-----------)  = - ATAN2(2x, 1 - x  - y )
  42  *          2       (     2    2)    2
  43  *                  (1 - x  - y )
  44  *
  45  *               ( 2         2)
  46  *          1    (x  +  (y+1) )      1                  4y
  47  * Im w  =  - log(------------) .=  --- log [ 1 + ------------- ]
  48  *          4    ( 2         2)      4              2         2
  49  *               (x  +  (y-1) )                    x  +  (y-1)
  50  *

  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 __catan = catan
  31 
  32 /* INDENT OFF */
  33 /*
  34  * dcomplex catan(dcomplex z);
  35  *
  36  * If
  37  *     z = x + iy,
  38  *
  39  * then
  40  *          1       (    2x     )    1                2    2
  41  * Re w  =  - arctan(-----------)  = - ATAN2(2x, 1 - x  - y )
  42  *          2       (     2    2)    2
  43  *                  (1 - x  - y )
  44  *
  45  *               ( 2         2)
  46  *          1    (x  +  (y+1) )      1                  4y
  47  * Im w  =  - log(------------) .=  --- log [ 1 + ------------- ]
  48  *          4    ( 2         2)      4              2         2
  49  *               (x  +  (y-1) )                    x  +  (y-1)
  50  *