    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.math3.ode;
    019
    020    import java.io.Serializable;
    021
    022    import org.apache.commons.math3.exception.DimensionMismatchException;
    023
    024    /**
    025     * Class mapping the part of a complete state or derivative that pertains
    026     * to a specific differential equation.
    027     * <p>
    028     * Instances of this class are guaranteed to be immutable.
    029     * </p>
    030     * @see SecondaryEquations
    031     * @version $Id: EquationsMapper.java 1416643 2012-12-03 19:37:14Z tn $
    032     * @since 3.0
    033     */
    034    public class EquationsMapper implements Serializable {
    035
    036        /** Serializable UID. */
    037        private static final long serialVersionUID = 20110925L;
    038
    039        /** Index of the first equation element in complete state arrays. */
    040        private final int firstIndex;
    041
    042        /** Dimension of the secondary state parameters. */
    043        private final int dimension;
    044
    045        /** simple constructor.
    046         * @param firstIndex index of the first equation element in complete state arrays
    047         * @param dimension dimension of the secondary state parameters
    048         */
    049        public EquationsMapper(final int firstIndex, final int dimension) {
    050            this.firstIndex = firstIndex;
    051            this.dimension  = dimension;
    052        }
    053
    054        /** Get the index of the first equation element in complete state arrays.
    055         * @return index of the first equation element in complete state arrays
    056         */
    057        public int getFirstIndex() {
    058            return firstIndex;
    059        }
    060
    061        /** Get the dimension of the secondary state parameters.
    062         * @return dimension of the secondary state parameters
    063         */
    064        public int getDimension() {
    065            return dimension;
    066        }
    067
    068        /** Extract equation data from a complete state or derivative array.
    069         * @param complete complete state or derivative array from which
    070         * equation data should be retrieved
    071         * @param equationData placeholder where to put equation data
    072         * @throws DimensionMismatchException if the dimension of the equation data does not
    073         * match the mapper dimension
    074         */
    075        public void extractEquationData(double[] complete, double[] equationData)
    076            throws DimensionMismatchException {
    077            if (equationData.length != dimension) {
    078                throw new DimensionMismatchException(equationData.length, dimension);
    079            }
    080            System.arraycopy(complete, firstIndex, equationData, 0, dimension);
    081        }
    082
    083        /** Insert equation data into a complete state or derivative array.
    084         * @param equationData equation data to be inserted into the complete array
    085         * @param complete placeholder where to put equation data (only the
    086         * part corresponding to the equation will be overwritten)
    087         * @throws DimensionMismatchException if the dimension of the equation data does not
    088         * match the mapper dimension
    089         */
    090        public void insertEquationData(double[] equationData, double[] complete)
    091            throws DimensionMismatchException {
    092            if (equationData.length != dimension) {
    093                throw new DimensionMismatchException(equationData.length, dimension);
    094            }
    095            System.arraycopy(equationData, 0, complete, firstIndex, dimension);
    096        }
    097
    098    }