/*
 * 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.ConvergenceException;
import org.apache.commons.math.ConvergingAlgorithm;
import org.apache.commons.math.FunctionEvaluationException;
import org.apache.commons.math.analysis.UnivariateRealFunction;

/**
 * Interface for (univariate real) optimization algorithms.
 * 
 * @version $Revision$ $Date$
 * @since 2.0
 */
public interface UnivariateRealOptimizer extends ConvergingAlgorithm {

	/**
	 * 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 evaluations of the objective function.
	 * <p>
	 * The number of evaluations corresponds to the last call to the
	 * {@link #optimize(UnivariateRealFunction, GoalType, double, 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();

	/**
	 * Find an optimum in the given interval.
	 * <p>
	 * An optimizer may require that the interval brackets a single optimum.
	 * </p>
	 * 
	 * @param f
	 *            the function to optimize.
	 * @param goalType
	 *            type of optimization goal: either {@link GoalType#MAXIMIZE} or
	 *            {@link GoalType#MINIMIZE}
	 * @param min
	 *            the lower bound for the interval.
	 * @param max
	 *            the upper bound for the interval.
	 * @return a value where the function is optimum
	 * @throws ConvergenceException
	 *             if the maximum iteration count is exceeded or the optimizer
	 *             detects convergence problems otherwise.
	 * @throws FunctionEvaluationException
	 *             if an error occurs evaluating the function
	 * @throws IllegalArgumentException
	 *             if min > max or the endpoints do not satisfy the requirements
	 *             specified by the optimizer
	 */
	double optimize(UnivariateRealFunction f, GoalType goalType, double min, double max)
			throws ConvergenceException, FunctionEvaluationException;

	/**
	 * Find an optimum in the given interval, start at startValue.
	 * <p>
	 * An optimizer may require that the interval brackets a single optimum.
	 * </p>
	 * 
	 * @param f
	 *            the function to optimize.
	 * @param goalType
	 *            type of optimization goal: either {@link GoalType#MAXIMIZE} or
	 *            {@link GoalType#MINIMIZE}
	 * @param min
	 *            the lower bound for the interval.
	 * @param max
	 *            the upper bound for the interval.
	 * @param startValue
	 *            the start value to use
	 * @return a value where the function is optimum
	 * @throws ConvergenceException
	 *             if the maximum iteration count is exceeded or the optimizer
	 *             detects convergence problems otherwise.
	 * @throws FunctionEvaluationException
	 *             if an error occurs evaluating the function
	 * @throws IllegalArgumentException
	 *             if min > max or the arguments do not satisfy the requirements
	 *             specified by the optimizer
	 */
	double optimize(UnivariateRealFunction f, GoalType goalType, double min, double max, double startValue)
			throws ConvergenceException, FunctionEvaluationException;

	/**
	 * Get the result of the last run of the optimizer.
	 * 
	 * @return the last result.
	 * @throws IllegalStateException
	 *             if there is no result available, either because no result was
	 *             yet computed or the last attempt failed.
	 */
	double getResult();

	/**
	 * Get the result of the last run of the optimizer.
	 * 
	 * @return the value of the function at the last result.
	 * @throws IllegalStateException
	 *             if there is no result available, either because no result was
	 *             yet computed or the last attempt failed.
	 */
	double getFunctionValue();

}