45 lines
1.7 KiB
C
45 lines
1.7 KiB
C
/****************************************************************************
|
|
* libs/libc/math/lib_tanhf.c
|
|
*
|
|
* This file is a part of NuttX:
|
|
*
|
|
* Copyright (C) 2012 Gregory Nutt. All rights reserved.
|
|
* Ported by: Darcy Gong
|
|
*
|
|
* It derives from the Rhombus OS math library by Nick Johnson which has
|
|
* a compatible, MIT-style license:
|
|
*
|
|
* Copyright (C) 2009, 2010 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>
|
|
|
|
/****************************************************************************
|
|
* Public Functions
|
|
****************************************************************************/
|
|
|
|
float tanhf(float x)
|
|
{
|
|
float x0 = expf(x);
|
|
float x1 = 1.0F / x0;
|
|
|
|
return ((x0 - x1) / (x0 + x1));
|
|
}
|