001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018 package org.apache.commons.math.linear;
019
020 /**
021 * Interface defining a visitor for matrix entries.
022 *
023 * @see DefaultRealMatrixChangingVisitor
024 * @version $Revision: 811685 $ $Date: 2009-09-05 13:36:48 -0400 (Sat, 05 Sep 2009) $
025 * @since 2.0
026 */
027 public interface RealMatrixChangingVisitor {
028
029 /**
030 * Start visiting a matrix.
031 * <p>This method is called once before any entry of the matrix is visited.</p>
032 * @param rows number of rows of the matrix
033 * @param columns number of columns of the matrix
034 * @param startRow Initial row index
035 * @param endRow Final row index (inclusive)
036 * @param startColumn Initial column index
037 * @param endColumn Final column index (inclusive)
038 */
039 void start(int rows, int columns,
040 int startRow, int endRow, int startColumn, int endColumn);
041
042 /**
043 * Visit one matrix entry.
044 * @param row row index of the entry
045 * @param column column index of the entry
046 * @param value current value of the entry
047 * @return the new value to be set for the entry
048 * @throws MatrixVisitorException if something wrong occurs
049 */
050 double visit(int row, int column, double value)
051 throws MatrixVisitorException;
052
053 /**
054 * End visiting a matrix.
055 * <p>This method is called once after all entries of the matrix have been visited.</p>
056 * @return the value that the <code>walkInXxxOrder</code> must return
057 */
058 double end();
059
060 }