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 package org.apache.commons.math4.legacy.linear;
18
19 /**
20 * This interface defines a visitor for the entries of a vector. Visitors
21 * implementing this interface may alter the entries of the vector being
22 * visited.
23 *
24 * @since 3.1
25 */
26 public interface RealVectorChangingVisitor {
27 /**
28 * Start visiting a vector. This method is called once, before any entry
29 * of the vector is visited.
30 *
31 * @param dimension the size of the vector
32 * @param start the index of the first entry to be visited
33 * @param end the index of the last entry to be visited (inclusive)
34 */
35 void start(int dimension, int start, int end);
36
37 /**
38 * Visit one entry of the vector.
39 *
40 * @param index the index of the entry being visited
41 * @param value the value of the entry being visited
42 * @return the new value of the entry being visited
43 */
44 double visit(int index, double value);
45
46 /**
47 * End visiting a vector. This method is called once, after all entries of
48 * the vector have been visited.
49 *
50 * @return the value returned by
51 * {@link RealVector#walkInDefaultOrder(RealVectorChangingVisitor)},
52 * {@link RealVector#walkInDefaultOrder(RealVectorChangingVisitor, int, int)},
53 * {@link RealVector#walkInOptimizedOrder(RealVectorChangingVisitor)}
54 * or
55 * {@link RealVector#walkInOptimizedOrder(RealVectorChangingVisitor, int, int)}
56 */
57 double end();
58 }