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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 import org.apache.commons.math.FieldElement;
     21 import org.apache.commons.math.linear.MatrixVisitorException;
     22 
     23 /**
     24  * Interface defining a visitor for matrix entries.
     25  *
     26  * @param <T> the type of the field elements
     27  * @version $Revision: 1073158 $ $Date: 2011-02-21 22:46:52 +0100 (lun. 21 fvr. 2011) $
     28  * @since 2.0
     29  */
     30 public interface FieldMatrixChangingVisitor<T extends FieldElement<?>> {
     31 
     32     /**
     33      * Start visiting a matrix.
     34      * <p>This method is called once before any entry of the matrix is visited.</p>
     35      * @param rows number of rows of the matrix
     36      * @param columns number of columns of the matrix
     37      * @param startRow Initial row index
     38      * @param endRow Final row index (inclusive)
     39      * @param startColumn Initial column index
     40      * @param endColumn Final column index (inclusive)
     41      */
     42     void start(int rows, int columns,
     43                int startRow, int endRow, int startColumn, int endColumn);
     44 
     45     /**
     46      * Visit one matrix entry.
     47      * @param row row index of the entry
     48      * @param column column index of the entry
     49      * @param value current value of the entry
     50      * @return the new value to be set for the entry
     51      * @throws MatrixVisitorException if something wrong occurs
     52      */
     53     T visit(int row, int column, T value)
     54         throws MatrixVisitorException;
     55 
     56     /**
     57      * End visiting a matrix.
     58      * <p>This method is called once after all entries of the matrix have been visited.</p>
     59      * @return the value that the <code>walkInXxxOrder</code> must return
     60      */
     61     T end();
     62 
     63 }
     64