/* Copyright (C) 2002 Univ. of Massachusetts Amherst, Computer Science Dept.
   This file is part of "MALLET" (MAchine Learning for LanguagE Toolkit).
   http://www.cs.umass.edu/~mccallum/mallet
   This software is provided under the terms of the Common Public License,
   version 1.0, as published by http://www.opensource.org.  For further
   information, see the file `LICENSE' included with this distribution. */




/** 
   @author Andrew McCallum <a href="mailto:mccallum@cs.umass.edu">mccallum@cs.umass.edu</a>
 */

package cc.mallet.optimize;

import java.util.Collection;


public interface Optimizable
{
	public int getNumParameters ();

	public void getParameters (double[] buffer);
	public double getParameter (int index);

	public void setParameters (double[] params);
	public void setParameter (int index, double value);


	public interface ByValue extends Optimizable
	{
		public double getValue ();
	}

	public interface ByGradient extends Optimizable
	{
		public void getValueGradient (double[] buffer);
	}

	public interface ByGradientValue extends Optimizable
	{
		public void getValueGradient (double[] buffer);
		public double getValue ();
	}

	public interface ByHessian extends Optimizable.ByGradientValue
	{
		public void getValueHessian (double[][] buffer);
	}

	public interface ByVotedPerceptron extends Optimizable
	{
		public int getNumInstances ();
		public void getValueGradientForInstance (int instanceIndex, double[] bufffer);
	}

	public interface ByGISUpdate extends Optimizable
	{
		public double getValue();
		public void getGISUpdate (double[] buffer);
	}

	public interface ByBatchGradient extends Optimizable {
		public void getBatchValueGradient (double[] buffer, int batchIndex, int[] batchAssignments);
		public double getBatchValue(int batchIndex, int[] batchAssignments);
	}

	// gsc: for computing gradient from batches in multiple threads
	public interface ByCombiningBatchGradient extends Optimizable {
		public void getBatchValueGradient (double[] buffer, int batchIndex, int[] batchAssignments);
		public double getBatchValue(int batchIndex, int[] batchAssignments);
		public void combineGradients (Collection<double[]> batchGradients, double[] buffer);
		public int getNumBatches();
	}

}