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 /*
  27  * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
  28  * Use is subject to license terms.
  29  */
  30 
  31 #include "libm.h"
  32 
  33 
  34 /*
  35  * float __k_sin(double x);
  36  * kernel (float) sin function on [-pi/4, pi/4], pi/4 ~ 0.785398164
  37  * Input x is in double and assumed to be bounded by ~pi/4 in magnitude.
  38  *
  39  * Method: Let z = x * x, then
  40  *      S(x) = x(S0 + S1*z)(S2 + S3*z + z*z)
  41  * where
  42  *      S0 =   1.85735322054308378716204874632872525989806770558e-0003,
  43  *      S1 =  -1.95035094218403635082921458859320791358115801259e-0004,
  44  *      S2 =   5.38400550766074785970952495168558701485841707252e+0002,
  45  *      S3 =  -3.31975110777873728964197739157371509422022905947e+0001,
  46  *
  47  * The remez error is bound by  |(sin(x) - S(x))/x| < 2**(-28.2)
  48  *
  49  * Constants:
  50  * The hexadecimal values are the intended ones for the following constants.
  51  * The decimal values may be used, provided that the compiler will convert
  52  * from decimal to binary accurately enough to produce the hexadecimal values
  53  * shown.
  54  */
  55 
  56 static const double q[] = {
  57 /* S0 = */
  58         1.85735322054308378716204874632872525989806770558e-0003,
  59 /* S1 = */ -1.95035094218403635082921458859320791358115801259e-0004,
  60 /* S2 = */ 5.38400550766074785970952495168558701485841707252e+0002,
  61 /* S3 = */ -3.31975110777873728964197739157371509422022905947e+0001, };
  62 
  63 #define S0              q[0]
  64 #define S1              q[1]
  65 #define S2              q[2]
  66 #define S3              q[3]
  67 
  68 float
  69 __k_sinf(double x)
  70 {
  71         float ft;
  72         double z;
  73         int hx;
  74 
  75         hx = ((int *)&x)[HIWORD];           /* hx = leading x */
  76 
  77         if ((hx & ~0x80000000) < 0x3f100000) {   /* if |x| < 2**-14 */
  78                 ft = (float)x;
  79 
  80                 if ((int)x == 0)                /* raise inexact if x != 0 */
  81                         return (ft);
  82         }
  83 
  84         z = x * x;
  85         ft = (float)((x * (S0 + z * S1)) * (S2 + z * (S3 + z)));
  86         return (ft);
  87 }