nuttx/libs/libc/math/lib_erfl.c
Gregory Nutt cf99fb40c9 This commit moves all of the libraries under a common directory called libs/. This most certainly break libcxx and uClibc++ for now.
Squashed commit of the following:

    libs/libxx:  Fix some confusing in naming.  If the directory is called libxx, then the library must be libxx.a (unless perhaps LIBCXX is selected).
    libs/:  Fix paths in moved library directories.
    libs:  Brute force move of libc, libnx, and libxx to libs.  Cannot yet build it in that configuration.
2018-05-29 13:21:26 -06:00

72 lines
2.8 KiB
C

/****************************************************************************
* libs/libc/math/lib_erfl.c
*
* Copyright (C) 2015 Brennan Ashton. All rights reserved.
* Author: Brennan Ashton <bashton@brennanashton.com>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <nuttx/compiler.h>
#include <math.h>
/****************************************************************************
* Public Functions
****************************************************************************/
#define A1 0.254829592
#define A2 (-0.284496736)
#define A3 1.421413741
#define A4 (-1.453152027)
#define A5 1.061405429
#define P 0.3275911
#ifdef CONFIG_HAVE_LONG_DOUBLE
long double erfl(long double x)
{
/* This implementation comes from the Handbook of Mathmatical Functions
* The implementations in this book are not protected by copyright.
* erf comes from formula 7.1.26
*/
long double t, z;
z = fabsl(x);
t = 1.0 / (1.0 + P * z);
t = 1.0 - (((((A5 * t + A4) * t) + A3) * t + A2) * t + A1) * t * expl(-z * z);
return copysignl(t, x);
}
#endif