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 package org.apache.commons.math3.linear;
018
019 /**
020 * This interface defines a visitor for the entries of a vector. Visitors
021 * implementing this interface may alter the entries of the vector being
022 * visited.
023 *
024 * @version $Id: RealVectorChangingVisitor.java 1416643 2012-12-03 19:37:14Z tn $
025 * @since 3.1
026 */
027 public interface RealVectorChangingVisitor {
028 /**
029 * Start visiting a vector. This method is called once, before any entry
030 * of the vector is visited.
031 *
032 * @param dimension the size of the vector
033 * @param start the index of the first entry to be visited
034 * @param end the index of the last entry to be visited (inclusive)
035 */
036 void start(int dimension, int start, int end);
037
038 /**
039 * Visit one entry of the vector.
040 *
041 * @param index the index of the entry being visited
042 * @param value the value of the entry being visited
043 * @return the new value of the entry being visited
044 */
045 double visit(int index, double value);
046
047 /**
048 * End visiting a vector. This method is called once, after all entries of
049 * the vector have been visited.
050 *
051 * @return the value returned by
052 * {@link RealVector#walkInDefaultOrder(RealVectorChangingVisitor)},
053 * {@link RealVector#walkInDefaultOrder(RealVectorChangingVisitor, int, int)},
054 * {@link RealVector#walkInOptimizedOrder(RealVectorChangingVisitor)}
055 * or
056 * {@link RealVector#walkInOptimizedOrder(RealVectorChangingVisitor, int, int)}
057 */
058 double end();
059 }