001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018package org.apache.commons.math3.optimization;
019
020/**
021 * This interface specifies how to check if an optimization algorithm has
022 * converged.
023 * <br/>
024 * Deciding if convergence has been reached is a problem-dependent issue. The
025 * user should provide a class implementing this interface to allow the
026 * optimization algorithm to stop its search according to the problem at hand.
027 * <br/>
028 * For convenience, three implementations that fit simple needs are already
029 * provided: {@link SimpleValueChecker}, {@link SimpleVectorValueChecker} and
030 * {@link SimplePointChecker}. The first two consider that convergence is
031 * reached when the objective function value does not change much anymore, it
032 * does not use the point set at all.
033 * The third one considers that convergence is reached when the input point
034 * set does not change much anymore, it does not use objective function value
035 * at all.
036 *
037 * @param <PAIR> Type of the (point, objective value) pair.
038 *
039 * @see org.apache.commons.math3.optimization.SimplePointChecker
040 * @see org.apache.commons.math3.optimization.SimpleValueChecker
041 * @see org.apache.commons.math3.optimization.SimpleVectorValueChecker
042 *
043 * @deprecated As of 3.1 (to be removed in 4.0).
044 * @since 3.0
045 */
046@Deprecated
047public interface ConvergenceChecker<PAIR> {
048    /**
049     * Check if the optimization algorithm has converged.
050     *
051     * @param iteration Current iteration.
052     * @param previous Best point in the previous iteration.
053     * @param current Best point in the current iteration.
054     * @return {@code true} if the algorithm is considered to have converged.
055     */
056    boolean converged(int iteration, PAIR previous, PAIR current);
057}