code: /*******************************************************************************
   * Copyright (c) 2013 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
   ******************************************************************************/
  // Copyright (c) 2009,2010 Attila Kovacs
  
  package crush.instrument;
  
  import java.lang.reflect.*;
  
  import crush.Channel;
  import crush.ChannelGroup;
  import crush.CorrelatedMode;
  
  public class FieldGradientMode extends CorrelatedMode {
  	/**
  	 * 
  	 */
  	private static final long serialVersionUID = 6661319100565424381L;
  	private Field field;
  
  	public FieldGradientMode(Field field) {
  		this.field = field;
  	}
  	
  	public FieldGradientMode(Field field, ChannelGroup<?> channels) {
  		this.field = field;
  		setChannels(channels);
  	}
  	
  	public Field getField() { return field; }
  
  	@Override
  	public void setChannels(ChannelGroup<?> channels) {
  		super.setChannels(channels);
  		name += ":" + field.getName();
  	}
  	
  	@Override
  	public float[] getGains(boolean validate) throws Exception {
  		float[] gains = super.getGains(validate);
  		
  		double sumwg = 0.0, sumw = 0.0;
  		for(Channel channel : getChannels()) if(channel.isUnflagged()) {
  			sumwg += channel.weight * field.getDouble(channel);
  			sumw += channel.weight;	
  		}
  		
  		float aveg = sumw > 0.0 ? (float)(sumwg / sumw) : 0.0F;
  
  		for(int c=size(); --c >= 0; ) {
  			Channel channel = getChannel(c);
  			gains[c] = field.getFloat(channel) - aveg;
  		}
  
  		return gains;
  	}
  }
  
  