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TarsosDSP library
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/*
*      _______                       _____   _____ _____  
*     |__   __|                     |  __ \ / ____|  __ \ 
*        | | __ _ _ __ ___  ___  ___| |  | | (___ | |__) |
*        | |/ _` | '__/ __|/ _ \/ __| |  | |\___ \|  ___/ 
*        | | (_| | |  \__ \ (_) \__ \ |__| |____) | |     
*        |_|\__,_|_|  |___/\___/|___/_____/|_____/|_|     
*                                                         
* -------------------------------------------------------------
*
* TarsosDSP is developed by Joren Six at IPEM, University Ghent
*  
* -------------------------------------------------------------
*
*  Info: http://0110.be/tag/TarsosDSP
*  Github: https://github.com/JorenSix/TarsosDSP
*  Releases: http://0110.be/releases/TarsosDSP/
*  
*  TarsosDSP includes modified source code by various authors,
*  for credits and info, see README.
* 
*/

/*
 *  Copyright (c) 2007 - 2008 by Damien Di Fede 
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU Library 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 Library General Public License for more details.
 *
 *   You should have received a copy of the GNU Library General Public
 *   License along with this program; if not, write to the Free Software
 *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

package be.tarsos.dsp.util.fft;

/**
 * A Gauss window function.
 * 
 * @author Damien Di Fede
 * @author Corban Brook
 * @see The
 *      Gauss Window
 */
public class GaussWindow extends WindowFunction {
	double alpha;

	/**
	 * Constructs a Gauss window function.
	 * 
	 * @param alpha
	 */
	public GaussWindow(double alpha) {
		if (alpha < 0.0 || alpha > 0.5) {
			new IllegalArgumentException(
					"Range for GaussWindow out of bounds. Value must be <= 0.5");
		} else {
			this.alpha = alpha;
		}
	}

	/** Constructs a Gauss window with a default alpha value of 0.25 */
	public GaussWindow() {
		this(0.25);
	}

	protected float value(int length, int index) {
		return (float) Math.pow(Math.E,	-0.5 * Math.pow((index - (length - 1) / (double) 2)	/ (this.alpha * (length - 1) / (double) 2),(double) 2));
	}
}