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/************************************************************************
* lib/math/lib_sinl.c
*
* This file is a part of NuttX:
*
* Copyright (C) 2012 Gregory Nutt. All rights reserved.
* Ported by: Darcy Gong
*
* It derives from the Rhombs OS math library by Nick Johnson which has
* a compatibile, MIT-style license:
*
* Copyright (C) 2009-2011 Nick Johnson <nickbjohnson4224 at gmail.com>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
************************************************************************/
/************************************************************************
* Included Files
************************************************************************/
#include <nuttx/config.h>
#include <nuttx/compiler.h>
#include <sys/types.h>
#include <math.h>
#if CONFIG_HAVE_LONG_DOUBLE
/************************************************************************
* Private Data
************************************************************************/
static long double _ldbl_inv_fact[] =
{
1.0 / 1.0, // 1 / 1!
1.0 / 6.0, // 1 / 3!
1.0 / 120.0, // 1 / 5!
1.0 / 5040.0, // 1 / 7!
1.0 / 362880.0, // 1 / 9!
1.0 / 39916800.0, // 1 / 11!
1.0 / 6227020800.0, // 1 / 13!
1.0 / 1307674368000.0, // 1 / 15!
1.0 / 355687428096000.0, // 1 / 17!
1.0 / 121645100408832000.0, // 1 / 19!
};
/************************************************************************
* Public Functions
************************************************************************/
long double sinl(long double x)
{
long double x_squared;
long double sin_x;
size_t i;
/* Move x to [-pi, pi) */
x = fmodl(x, 2 * M_PI);
if (x >= M_PI)
{
x -= 2 * M_PI;
}
if (x < -M_PI)
{
x += 2 * M_PI;
}
/* Move x to [-pi/2, pi/2) */
if (x >= M_PI_2)
{
x = M_PI - x;
}
if (x < -M_PI_2)
{
x = -M_PI - x;
}
x_squared = x * x;
sin_x = 0.0;
/* Perform Taylor series approximation for sin(x) with ten terms */
for (i = 0; i < 10; i++)
{
if (i % 2 == 0)
{
sin_x += x * _ldbl_inv_fact[i];
}
else
{
sin_x -= x * _ldbl_inv_fact[i];
}
x *= x_squared;
}
return sin_x;
}
#endif
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