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ESP - An EEG Signal Processing Library

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/*
 *  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 ddf.minim.analysis;

// TODO: Auto-generated Javadoc
/**
 * A Hann window function.
 * 
 * @author Damien Di Fede
 * @author Corban Brook
 * @see The
 *      Hann Window
 */
public class HannWindow extends WindowFunction {
  /** Constructs a Hann window. */
  public HannWindow() {
  }

  /* (non-Javadoc)
   * @see ddf.minim.analysis.WindowFunction#value(int, int)
   */
  protected double value(int length, int index) {
    return 0.5f * (1f - (double) Math.cos(TWO_PI * index / (length - 1f)));
  }
}