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 2006 Sun Microsystems, Inc.  All rights reserved.
  26  * Use is subject to license terms.
  27  */
  28 
  29 #pragma weak atan2 = __atan2
  30 
  31 #include "libm.h"
  32 
  33 /*
  34  * Let t(0) = 1 and for i = 1, ..., 160, let t(i) be the slope of
  35  * the line bisecting the conical hull of the set of points (x,y)
  36  * where x and y are positive normal floating point numbers and
  37  * the high order words hx and hy of their binary representations
  38  * satisfy |hx - hy - i * 0x8000| <= 0x4000.  Then:
  39  *
  40  * TBL[4*i+2] is t(i) rounded to 21 significant bits (i.e., the
  41  *   low order word is zero), and
  42  *
  43  * TBL[4*i] + TBL[4*i+1] form a doubled-double approximation to
  44  *   atan(TBL[4*i+2]).
  45  *
  46  * Finally, TBL[4*161] = TBL[4*161+1] = TBL[4*161+2] = 0.
  47  *
  48  * Now for any (x,y) with 0 < y <= x and any 0 < t <= 1,  we have
  49  * atan(y/x) = atan(t) + atan((y-t*x)/(x+t*y)).  By choosing t =

   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 2006 Sun Microsystems, Inc.  All rights reserved.
  26  * Use is subject to license terms.
  27  */
  28 
  29 #pragma weak __atan2 = atan2
  30 
  31 #include "libm.h"
  32 
  33 /*
  34  * Let t(0) = 1 and for i = 1, ..., 160, let t(i) be the slope of
  35  * the line bisecting the conical hull of the set of points (x,y)
  36  * where x and y are positive normal floating point numbers and
  37  * the high order words hx and hy of their binary representations
  38  * satisfy |hx - hy - i * 0x8000| <= 0x4000.  Then:
  39  *
  40  * TBL[4*i+2] is t(i) rounded to 21 significant bits (i.e., the
  41  *   low order word is zero), and
  42  *
  43  * TBL[4*i] + TBL[4*i+1] form a doubled-double approximation to
  44  *   atan(TBL[4*i+2]).
  45  *
  46  * Finally, TBL[4*161] = TBL[4*161+1] = TBL[4*161+2] = 0.
  47  *
  48  * Now for any (x,y) with 0 < y <= x and any 0 < t <= 1,  we have
  49  * atan(y/x) = atan(t) + atan((y-t*x)/(x+t*y)).  By choosing t =