code: /*******************************************************************************
   * Copyright (c) 2016 Attila Kovacs <attila[AT]sigmyne.com>.
   * All rights reserved. 
   * 
   * This file is part of crush.
   * 
   *     crush 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 3 of the License, or
   *     (at your option) any later version.
   * 
   *     crush 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 crush.  If not, see <http://www.gnu.org/licenses/>.
   * 
   * Contributors:
   *     Attila Kovacs <attila[AT]sigmyne.com> - initial API and implementation
   ******************************************************************************/
  package crush.instrument;
  
  import java.io.Serializable;
  
  import crush.Channel;
  import crush.CorrelatedMode;
  import crush.Mode;
  
  
  public abstract class ZeroMeanGains implements Serializable, GainProvider {
  	/**
  	 * 
  	 */
  	private static final long serialVersionUID = -5916984290768232863L;
  	
  	private double aveG = 0.0;
  	
  	@Override
  	public final double getGain(Channel c) throws Exception {
  	    double g0 = getRelativeGain(c);
  	    return Double.isNaN(g0) ? 0.0 : g0 - aveG;
  	}
  	
  	@Override
  	public final void setGain(Channel c, double value) throws Exception {
  		setRawGain(c, value + aveG);
  	}
  	
  	public abstract double getRelativeGain(Channel c) throws Exception;
  	
  	public abstract void setRawGain(Channel c, double value) throws Exception;
  	
  	@Override
  	public void validate(Mode mode) throws Exception {	  
  		double sum = 0.0, sumw = 0.0;
  		
  		final int skipFlags = mode instanceof CorrelatedMode ? ((CorrelatedMode) mode).skipFlags : 0;
  		
  		for(int k=mode.size(); --k >= 0; ) {
  			final Channel channel = mode.getChannel(k);
  			if(channel.isFlagged(skipFlags)) continue;
  
  			final double g = getRelativeGain(channel);
  			if(Double.isNaN(g)) continue;
  				
  			sum += channel.weight * g;
  			sumw += channel.weight;
  		}
  		
  		aveG = sumw > 0.0 ? sum / sumw : 0.0;
  	}
  
  }
  