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
18package org.apache.commons.math.linear;
19
20import org.apache.commons.math.linear.MatrixVisitorException;
21
22/**
23 * Interface defining a visitor for matrix entries.
24 *
25 * @see DefaultRealMatrixChangingVisitor
26 * @version $Revision: 1073158 $ $Date: 2011-02-21 22:46:52 +0100 (lun. 21 févr. 2011) $
27 * @since 2.0
28 */
29public interface RealMatrixChangingVisitor {
30
31    /**
32     * Start visiting a matrix.
33     * <p>This method is called once before any entry of the matrix is visited.</p>
34     * @param rows number of rows of the matrix
35     * @param columns number of columns of the matrix
36     * @param startRow Initial row index
37     * @param endRow Final row index (inclusive)
38     * @param startColumn Initial column index
39     * @param endColumn Final column index (inclusive)
40     */
41    void start(int rows, int columns,
42               int startRow, int endRow, int startColumn, int endColumn);
43
44    /**
45     * Visit one matrix entry.
46     * @param row row index of the entry
47     * @param column column index of the entry
48     * @param value current value of the entry
49     * @return the new value to be set for the entry
50     * @throws MatrixVisitorException if something wrong occurs
51     */
52    double visit(int row, int column, double value)
53        throws MatrixVisitorException;
54
55    /**
56     * End visiting a matrix.
57     * <p>This method is called once after all entries of the matrix have been visited.</p>
58     * @return the value that the <code>walkInXxxOrder</code> must return
59     */
60    double end();
61
62}
63