/*****************************************************************************/

/*
 *      rrcfreq.c  --  Square Root Raised Cosine Function (Frequency Domain).
 *
 *      Copyright (C) 2001, 2002
 *        Thomas Sailer (t.sailer@alumni.ethz.ch)
 *
 *      This program is free software; you can redistribute it and/or modify
 *      it under the terms of the GNU General Public License as published by
 *      the Free Software Foundation; either version 2 of the License, or
 *      (at your option) any later version.
 *
 *      This program is distributed in the hope that it will be useful,
 *      but WITHOUT ANY WARRANTY; without even the implied warranty of
 *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *      GNU General Public License for more details.
 *
 *      You should have received a copy of the GNU General Public License
 *      along with this program; if not, write to the Free Software
 *      Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 *
 */

/*****************************************************************************/

#define _GNU_SOURCE

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

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

#include "raisedcosine.h"

/* --------------------------------------------------------------------- */

double root_raised_cosine_freq(double freq, double alpha)
{
	freq = fabs(freq);
	freq -= 0.5 * (1 - alpha);
	if (freq <= 0)
		return 1;
	if (freq >= alpha)
		return 0;
	freq /= alpha;
	freq *= M_PI;
	return sqrt(0.5 * (1 + cos(freq)));
}
