/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.commons.math.optimization;

import org.apache.commons.math.FunctionEvaluationException;
import org.apache.commons.math.analysis.MultivariateRealFunction;

/**
 * This interface represents an optimization algorithm for
 * {@link MultivariateRealFunction scalar objective functions}.
 * <p>
 * Optimization algorithms find the input point set that either {@link GoalType
 * maximize or minimize} an objective function.
 * </p>
 * 
 * @see DifferentiableMultivariateRealOptimizer
 * @see DifferentiableMultivariateVectorialOptimizer
 * @version $Revision$ $Date$
 * @since 2.0
 */
public interface MultivariateRealOptimizer {

	/**
	 * Set the maximal number of iterations of the algorithm.
	 * 
	 * @param maxIterations
	 *            maximal number of algorithm iterations
	 */
	void setMaxIterations(int maxIterations);

	/**
	 * Get the maximal number of iterations of the algorithm.
	 * 
	 * @return maximal number of iterations
	 */
	int getMaxIterations();

	/**
	 * Set the maximal number of functions evaluations.
	 * 
	 * @param maxEvaluations
	 *            maximal number of function evaluations
	 */
	void setMaxEvaluations(int maxEvaluations);

	/**
	 * Get the maximal number of functions evaluations.
	 * 
	 * @return maximal number of functions evaluations
	 */
	int getMaxEvaluations();

	/**
	 * Get the number of iterations realized by the algorithm.
	 * <p>
	 * The number of evaluations corresponds to the last call to the
	 * {@link #optimize(MultivariateRealFunction, GoalType, double[]) optimize}
	 * method. It is 0 if the method has not been called yet.
	 * </p>
	 * 
	 * @return number of iterations
	 */
	int getIterations();

	/**
	 * Get the number of evaluations of the objective function.
	 * <p>
	 * The number of evaluations corresponds to the last call to the
	 * {@link #optimize(MultivariateRealFunction, GoalType, double[]) optimize}
	 * method. It is 0 if the method has not been called yet.
	 * </p>
	 * 
	 * @return number of evaluations of the objective function
	 */
	int getEvaluations();

	/**
	 * Set the convergence checker.
	 * 
	 * @param checker
	 *            object to use to check for convergence
	 */
	void setConvergenceChecker(RealConvergenceChecker checker);

	/**
	 * Get the convergence checker.
	 * 
	 * @return object used to check for convergence
	 */
	RealConvergenceChecker getConvergenceChecker();

	/**
	 * Optimizes an objective function.
	 * 
	 * @param f
	 *            objective function
	 * @param goalType
	 *            type of optimization goal: either {@link GoalType#MAXIMIZE} or
	 *            {@link GoalType#MINIMIZE}
	 * @param startPoint
	 *            the start point for optimization
	 * @return the point/value pair giving the optimal value for objective
	 *         function
	 * @exception FunctionEvaluationException
	 *                if the objective function throws one during the search
	 * @exception OptimizationException
	 *                if the algorithm failed to converge
	 * @exception IllegalArgumentException
	 *                if the start point dimension is wrong
	 */
	RealPointValuePair optimize(MultivariateRealFunction f, GoalType goalType, double[] startPoint)
			throws FunctionEvaluationException, OptimizationException, IllegalArgumentException;

}
