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/*
* 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.math3.optim;
/**
* This interface specifies how to check if an optimization algorithm has converged. <br>
* Deciding if convergence has been reached is a problem-dependent issue. The user should provide a
* class implementing this interface to allow the optimization algorithm to stop its search
* according to the problem at hand. <br>
* For convenience, three implementations that fit simple needs are already provided: {@link
* SimpleValueChecker}, {@link SimpleVectorValueChecker} and {@link SimplePointChecker}. The first
* two consider that convergence is reached when the objective function value does not change much
* anymore, it does not use the point set at all. The third one considers that convergence is
* reached when the input point set does not change much anymore, it does not use objective function
* value at all.
*
* @param <PAIR> Type of the (point, objective value) pair.
* @see org.apache.commons.math3.optim.SimplePointChecker
* @see org.apache.commons.math3.optim.SimpleValueChecker
* @see org.apache.commons.math3.optim.SimpleVectorValueChecker
* @since 3.0
*/
public interface ConvergenceChecker<PAIR> {
/**
* Check if the optimization algorithm has converged.
*
* @param iteration Current iteration.
* @param previous Best point in the previous iteration.
* @param current Best point in the current iteration.
* @return {@code true} if the algorithm is considered to have converged.
*/
boolean converged(int iteration, PAIR previous, PAIR current);
}
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