    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.DiagonalMatrix;
    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            weightMatrix = new DiagonalMatrix(weight);
    043        }
    044
    045        /**
    046         * @param weight Weight matrix.
    047         * @throws NonSquareMatrixException if the argument is not
    048         * a square matrix.
    049         */
    050        public Weight(RealMatrix weight) {
    051            if (weight.getColumnDimension() != weight.getRowDimension()) {
    052                throw new NonSquareMatrixException(weight.getColumnDimension(),
    053                                                   weight.getRowDimension());
    054            }
    055
    056            weightMatrix = weight.copy();
    057        }
    058
    059        /**
    060         * Gets the initial guess.
    061         *
    062         * @return the initial guess.
    063         */
    064        public RealMatrix getWeight() {
    065            return weightMatrix.copy();
    066        }
    067    }