66 lines
1.9 KiB
C
66 lines
1.9 KiB
C
/************************************************************************
|
|
* libc/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 <math.h>
|
|
#include <float.h>
|
|
|
|
/************************************************************************
|
|
* Public Functions
|
|
************************************************************************/
|
|
|
|
float asinf(float x)
|
|
{
|
|
long double y, y_sin, y_cos;
|
|
|
|
y = 0;
|
|
|
|
while (1)
|
|
{
|
|
y_sin = sinf(y);
|
|
y_cos = cosf(y);
|
|
|
|
if (y > M_PI_2 || y < -M_PI_2)
|
|
{
|
|
y = fmodf(y, M_PI);
|
|
}
|
|
|
|
if (y_sin + FLT_EPSILON >= x && y_sin - FLT_EPSILON <= x)
|
|
{
|
|
break;
|
|
}
|
|
|
|
y = y - (y_sin - x) / y_cos;
|
|
}
|
|
|
|
return y;
|
|
}
|
|
|