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/*****************************************************************************/
/*
* rcfreq.c -- 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 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 0.5 * (1 + cos(freq));
}
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