path: root/nuttx/lib/math/lib_tanh.c

/*
 * 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.
 */

#include <apps/math.h>
#include <float.h>

float tanhf(float x) {
	float x0 = expf(x);
	float x1 = 1.0 / x0;

	return ((x0 + x1) / (x0 - x1));
}

double tanh(double x) {
	double x0 = exp(x);
	double x1 = 1.0 / x0;

	return ((x0 + x1) / (x0 - x1));
}

long double tanhl(long double x) {
	long double x0 = exp(x);
	long double x1 = 1.0 / x0;

	return ((x0 + x1) / (x0 - x1));
}