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 * https://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 /*
19 * This is not the original file distributed by the Apache Software Foundation
20 * It has been modified by the Hipparchus project
21 */
22
23 package org.hipparchus.optim;
24
25 /**
26 * This interface specifies how to check if an optimization algorithm has
27 * converged.
28 * <br>
29 * Deciding if convergence has been reached is a problem-dependent issue. The
30 * user should provide a class implementing this interface to allow the
31 * optimization algorithm to stop its search according to the problem at hand.
32 * <br>
33 * For convenience, three implementations that fit simple needs are already
34 * provided: {@link SimpleValueChecker}, {@link SimpleVectorValueChecker} and
35 * {@link SimplePointChecker}. The first two consider that convergence is
36 * reached when the objective function value does not change much anymore, it
37 * does not use the point set at all.
38 * The third one considers that convergence is reached when the input point
39 * set does not change much anymore, it does not use objective function value
40 * at all.
41 *
42 * @param <P> Type of the (point, objective value) pair.
43 *
44 * @see org.hipparchus.optim.SimplePointChecker
45 * @see org.hipparchus.optim.SimpleValueChecker
46 * @see org.hipparchus.optim.SimpleVectorValueChecker
47 *
48 */
49 public interface ConvergenceChecker<P> {
50 /**
51 * Check if the optimization algorithm has converged.
52 *
53 * @param iteration Current iteration.
54 * @param previous Best point in the previous iteration.
55 * @param current Best point in the current iteration.
56 * @return {@code true} if the algorithm is considered to have converged.
57 */
58 boolean converged(int iteration, P previous, P current);
59 }