105 lines
2.7 KiB
C
105 lines
2.7 KiB
C
/************************************************************************
|
|
* lib/math/lib_sinf.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 <sys/types.h>
|
|
#include <math.h>
|
|
|
|
/************************************************************************
|
|
* Private Data
|
|
************************************************************************/
|
|
|
|
static float _flt_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!
|
|
};
|
|
|
|
/************************************************************************
|
|
* Public Functions
|
|
************************************************************************/
|
|
|
|
float sinf(float x)
|
|
{
|
|
float x_squared;
|
|
float sin_x;
|
|
size_t i;
|
|
|
|
/* Move x to [-pi, pi) */
|
|
|
|
x = fmodf(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 six terms */
|
|
|
|
for (i = 0; i < 6; i++)
|
|
{
|
|
if (i % 2 == 0)
|
|
{
|
|
sin_x += x * _flt_inv_fact[i];
|
|
}
|
|
else
|
|
{
|
|
sin_x -= x * _flt_inv_fact[i];
|
|
}
|
|
|
|
x *= x_squared;
|
|
}
|
|
|
|
return sin_x;
|
|
}
|