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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.linear;
19  
20  /**
21   * Interface defining a visitor for matrix entries.
22   * 
23   * @see DefaultRealMatrixPreservingVisitor
24   * @version $Revision: 778191 $ $Date: 2009-05-24 12:44:52 -0400 (Sun, 24 May 2009) $
25   * @since 2.0
26   */
27  public interface RealMatrixPreservingVisitor {
28  
29      /**
30       * Start visiting a matrix.
31       * <p>This method is called once before any entry of the matrix is visited.</p>
32       * @param rows number of rows of the matrix
33       * @param columns number of columns of the matrix
34       * @param startRow Initial row index
35       * @param endRow Final row index (inclusive)
36       * @param startColumn Initial column index
37       * @param endColumn Final column index (inclusive)
38       */
39      void start(int rows, int columns,
40                 int startRow, int endRow, int startColumn, int endColumn);
41  
42      /**
43       * Visit one matrix entry.
44       * @param row row index of the entry
45       * @param column column index of the entry
46       * @param value current value of the entry
47       * @throws MatrixVisitorException if something wrong occurs
48       */
49      void visit(int row, int column, double value)
50          throws MatrixVisitorException;
51  
52      /**
53       * End visiting a matrix.
54       * <p>This method is called once after all entries of the matrix have been visited.</p>
55       * @return the value that the <code>walkInXxxOrder</code> must return
56       */
57      double end();
58  
59  }