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.optim.nonlinear.vector;
018    
019    import org.apache.commons.math3.optim.OptimizationData;
020    import org.apache.commons.math3.linear.RealMatrix;
021    import org.apache.commons.math3.linear.MatrixUtils;
022    import org.apache.commons.math3.linear.NonSquareMatrixException;
023    
024    /**
025     * Weight matrix of the residuals between model and observations.
026     * <br/>
027     * Immutable class.
028     *
029     * @version $Id: Weight.java 1416643 2012-12-03 19:37:14Z tn $
030     * @since 3.1
031     */
032    public class Weight implements OptimizationData {
033        /** Weight matrix. */
034        private final RealMatrix weightMatrix;
035    
036        /**
037         * Creates a diagonal weight matrix.
038         *
039         * @param weight List of the values of the diagonal.
040         */
041        public Weight(double[] weight) {
042            final int dim = weight.length;
043            weightMatrix = MatrixUtils.createRealMatrix(dim, dim);
044            for (int i = 0; i < dim; i++) {
045                weightMatrix.setEntry(i, i, weight[i]);
046            }
047        }
048    
049        /**
050         * @param weight Weight matrix.
051         * @throws NonSquareMatrixException if the argument is not
052         * a square matrix.
053         */
054        public Weight(RealMatrix weight) {
055            if (weight.getColumnDimension() != weight.getRowDimension()) {
056                throw new NonSquareMatrixException(weight.getColumnDimension(),
057                                                   weight.getRowDimension());
058            }
059    
060            weightMatrix = weight.copy();
061        }
062    
063        /**
064         * Gets the initial guess.
065         *
066         * @return the initial guess.
067         */
068        public RealMatrix getWeight() {
069            return weightMatrix.copy();
070        }
071    }