1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache License, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 */ 17 18 package org.apache.commons.math.optimization; 19 20 /** This interface specifies how to check if an {@link MultivariateRealOptimizer optimization 21 * algorithm} has converged. 22 * 23 * <p>Deciding if convergence has been reached is a problem-dependent issue. The 24 * user should provide a class implementing this interface to allow the optimization 25 * algorithm to stop its search according to the problem at hand.</p> 26 * <p>For convenience, two implementations that fit simple needs are already provided: 27 * {@link SimpleScalarValueChecker} and {@link SimpleRealPointChecker}. The first 28 * one considers convergence is reached when the objective function value does not 29 * change much anymore, it does not use the point set at all. The second one 30 * considers convergence is reached when the input point set does not change 31 * much anymore, it does not use objective function value at all.</p> 32 * 33 * @version $Revision: 799857 $ $Date: 2009-08-01 15:07:12 +0200 (sam. 01 aot 2009) $ 34 * @since 2.0 35 */ 36 37 public interface RealConvergenceChecker { 38 39 /** Check if the optimization algorithm has converged considering the last points. 40 * <p> 41 * This method may be called several time from the same algorithm iteration with 42 * different points. This can be detected by checking the iteration number at each 43 * call if needed. Each time this method is called, the previous and current point 44 * correspond to points with the same role at each iteration, so they can be 45 * compared. As an example, simplex-based algorithms call this method for all 46 * points of the simplex, not only for the best or worst ones. 47 * </p> 48 * @param iteration index of current iteration 49 * @param previous point from previous iteration 50 * @param current point from current iteration 51 * @return true if the algorithm is considered to have converged 52 */ 53 boolean converged(int iteration, RealPointValuePair previous, RealPointValuePair current); 54 55 } 56
