/*
 * 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.analysis.solvers;

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) rootfinding algorithms.
 * <p>
 * Implementations will search for only one zero in the given interval.
 * </p>
 * 
 * @version $Revision$ $Date$
 */
public interface UnivariateRealSolver extends ConvergingAlgorithm {

	/**
	 * Set the function value accuracy.
	 * <p>
	 * This is used to determine when an evaluated function value or some other
	 * value which is used as divisor is zero.
	 * </p>
	 * <p>
	 * This is a safety guard and it shouldn't be necessary to change this in
	 * general.
	 * </p>
	 * 
	 * @param accuracy
	 *            the accuracy.
	 * @throws IllegalArgumentException
	 *             if the accuracy can't be achieved by the solver or is
	 *             otherwise deemed unreasonable.
	 */
	void setFunctionValueAccuracy(double accuracy);

	/**
	 * Get the actual function value accuracy.
	 * 
	 * @return the accuracy
	 */
	double getFunctionValueAccuracy();

	/**
	 * Reset the actual function accuracy to the default. The default value is
	 * provided by the solver implementation.
	 */
	void resetFunctionValueAccuracy();

	/**
	 * Solve for a zero root in the given interval. A solver may require that
	 * the interval brackets a single zero root.
	 * 
	 * @param min
	 *            the lower bound for the interval.
	 * @param max
	 *            the upper bound for the interval.
	 * @return a value where the function is zero
	 * @throws ConvergenceException
	 *             if the maximum iteration count is exceeded or the solver
	 *             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 solver
	 * @deprecated replaced by
	 *             {@link #solve(UnivariateRealFunction, double, double)} since
	 *             2.0
	 */
	@Deprecated
	double solve(double min, double max) throws ConvergenceException, FunctionEvaluationException;

	/**
	 * Solve for a zero root in the given interval. A solver may require that
	 * the interval brackets a single zero root.
	 * 
	 * @param f
	 *            the function to solve.
	 * @param min
	 *            the lower bound for the interval.
	 * @param max
	 *            the upper bound for the interval.
	 * @return a value where the function is zero
	 * @throws ConvergenceException
	 *             if the maximum iteration count is exceeded or the solver
	 *             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 solver
	 * @since 2.0
	 */
	double solve(UnivariateRealFunction f, double min, double max)
			throws ConvergenceException, FunctionEvaluationException;

	/**
	 * Solve for a zero in the given interval, start at startValue. A solver may
	 * require that the interval brackets a single zero root.
	 * 
	 * @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 zero
	 * @throws ConvergenceException
	 *             if the maximum iteration count is exceeded or the solver
	 *             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 solver
	 * @deprecated replaced by
	 *             {@link #solve(UnivariateRealFunction, double, double, double)}
	 *             since 2.0
	 */
	@Deprecated
	double solve(double min, double max, double startValue)
			throws ConvergenceException, FunctionEvaluationException, IllegalArgumentException;

	/**
	 * Solve for a zero in the given interval, start at startValue. A solver may
	 * require that the interval brackets a single zero root.
	 * 
	 * @param f
	 *            the function to solve.
	 * @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 zero
	 * @throws ConvergenceException
	 *             if the maximum iteration count is exceeded or the solver
	 *             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 solver
	 * @since 2.0
	 */
	double solve(UnivariateRealFunction f, double min, double max, double startValue)
			throws ConvergenceException, FunctionEvaluationException, IllegalArgumentException;

	/**
	 * Get the result of the last run of the solver.
	 * 
	 * @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 solver.
	 * 
	 * @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();
}