Subversion Repositories openrisc

//===========================================================================

//

//      k_sin.c

//

//      Part of the standard mathematical function library

//

//===========================================================================

//####ECOSGPLCOPYRIGHTBEGIN####

// -------------------------------------------

// This file is part of eCos, the Embedded Configurable Operating System.

// Copyright (C) 1998, 1999, 2000, 2001, 2002 Red Hat, Inc.

//

// eCos is free software; you can redistribute it and/or modify it under

// the terms of the GNU General Public License as published by the Free

// Software Foundation; either version 2 or (at your option) any later version.

//

// eCos is distributed in the hope that it will be useful, but WITHOUT ANY

// WARRANTY; without even the implied warranty of MERCHANTABILITY or

// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

// for more details.

//

// You should have received a copy of the GNU General Public License along

// with eCos; if not, write to the Free Software Foundation, Inc.,

// 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.

//

// As a special exception, if other files instantiate templates or use macros

// or inline functions from this file, or you compile this file and link it

// with other works to produce a work based on this file, this file does not

// by itself cause the resulting work to be covered by the GNU General Public

// License. However the source code for this file must still be made available

// in accordance with section (3) of the GNU General Public License.

//

// This exception does not invalidate any other reasons why a work based on

// this file might be covered by the GNU General Public License.

//

// Alternative licenses for eCos may be arranged by contacting Red Hat, Inc.

// at http://sources.redhat.com/ecos/ecos-license/

// -------------------------------------------

//####ECOSGPLCOPYRIGHTEND####

//===========================================================================

//#####DESCRIPTIONBEGIN####

//

// Author(s):   jlarmour

// Contributors:  jlarmour

// Date:        1998-02-13

// Purpose:     

// Description: 

// Usage:       

//

//####DESCRIPTIONEND####

//

//===========================================================================

// CONFIGURATION

#include <pkgconf/libm.h>   // Configuration header

// Include the Math library?

#ifdef CYGPKG_LIBM     

// Derived from code with the following copyright

/* @(#)k_sin.c 1.3 95/01/18 */

/*

 * ====================================================

 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.

 *

 * Developed at SunSoft, a Sun Microsystems, Inc. business.

 * Permission to use, copy, modify, and distribute this

 * software is freely granted, provided that this notice

 * is preserved.

 * ====================================================

 */

/* __kernel_sin( x, y, iy)

 * kernel sin function on [-pi/4, pi/4], pi/4 ~ 0.7854

 * Input x is assumed to be bounded by ~pi/4 in magnitude.

 * Input y is the tail of x.

 * Input iy indicates whether y is 0. (if iy=0, y assume to be 0).

 *

 * Algorithm

 *      1. Since sin(-x) = -sin(x), we need only to consider positive x.

 *      2. if x < 2^-27 (hx<0x3e400000 0), return x with inexact if x!=0.

 *      3. sin(x) is approximated by a polynomial of degree 13 on

 *         [0,pi/4]

 *                               3            13

 *              sin(x) ~ x + S1*x + ... + S6*x

 *         where

 *

 *      |sin(x)         2     4     6     8     10     12  |     -58

 *      |----- - (1+S1*x +S2*x +S3*x +S4*x +S5*x  +S6*x   )| <= 2

 *      |  x                                               |

 *

 *      4. sin(x+y) = sin(x) + sin'(x')*y

 *                  ~ sin(x) + (1-x*x/2)*y

 *         For better accuracy, let

 *                   3      2      2      2      2

 *              r = x *(S2+x *(S3+x *(S4+x *(S5+x *S6))))

 *         then                   3    2

 *              sin(x) = x + (S1*x + (x *(r-y/2)+y))

 */

#include "mathincl/fdlibm.h"

static const double

half =  5.00000000000000000000e-01, /* 0x3FE00000, 0x00000000 */

S1  = -1.66666666666666324348e-01, /* 0xBFC55555, 0x55555549 */

S2  =  8.33333333332248946124e-03, /* 0x3F811111, 0x1110F8A6 */

S3  = -1.98412698298579493134e-04, /* 0xBF2A01A0, 0x19C161D5 */

S4  =  2.75573137070700676789e-06, /* 0x3EC71DE3, 0x57B1FE7D */

S5  = -2.50507602534068634195e-08, /* 0xBE5AE5E6, 0x8A2B9CEB */

S6  =  1.58969099521155010221e-10; /* 0x3DE5D93A, 0x5ACFD57C */

        double __kernel_sin(double x, double y, int iy)

{

        double z,r,v;

        int ix;

        ix = CYG_LIBM_HI(x)&0x7fffffff; /* high word of x */

        if(ix<0x3e400000)                       /* |x| < 2**-27 */

           {if((int)x==0) return x;}            /* generate inexact */

        z       =  x*x;

        v       =  z*x;

        r       =  S2+z*(S3+z*(S4+z*(S5+z*S6)));

        if(iy==0) return x+v*(S1+z*r);

        else      return x-((z*(half*y-v*r)-y)-v*S1);

}

#endif // ifdef CYGPKG_LIBM     

// EOF k_sin.c