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/************************************************************************
* libc/math/lib_sinh.c
*
* This file is a part of NuttX:
*
* Copyright (C) 2012, 2015 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, 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 <nuttx/config.h>
#include <nuttx/compiler.h>
#include <math.h>
/************************************************************************
* Public Functions
************************************************************************/
#ifdef CONFIG_HAVE_DOUBLE
double sinh(double x)
{
double y;
double z;
if (fabs(x) < 1E-5)
{
/* x + 1/3! * x^3 + 1/5! * x^5 + 1/7! * x^7 + ... */
z = x * x;
y = x * (1.0 + z / 6.0);
}
else
{
z = exp(x);
y = (z - 1.0 / z) / 2.0;
}
return y;
}
#endif
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