    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 org.apache.commons.math3.exception.DimensionMismatchException;
    021    import org.apache.commons.math3.exception.MaxCountExceededException;
    022
    023    /**
    024     * This interface allows users to add secondary differential equations to a primary
    025     * set of differential equations.
    026     * <p>
    027     * In some cases users may need to integrate some problem-specific equations along
    028     * with a primary set of differential equations. One example is optimal control where
    029     * adjoined parameters linked to the minimized hamiltonian must be integrated.
    030     * </p>
    031     * <p>
    032     * This interface allows users to add such equations to a primary set of {@link
    033     * FirstOrderDifferentialEquations first order differential equations}
    034     * thanks to the {@link
    035     * ExpandableStatefulODE#addSecondaryEquations(SecondaryEquations)}
    036     * method.
    037     * </p>
    038     * @see ExpandableStatefulODE
    039     * @version $Id: SecondaryEquations.java 1416643 2012-12-03 19:37:14Z tn $
    040     * @since 3.0
    041     */
    042    public interface SecondaryEquations {
    043
    044        /** Get the dimension of the secondary state parameters.
    045         * @return dimension of the secondary state parameters
    046         */
    047        int getDimension();
    048
    049        /** Compute the derivatives related to the secondary state parameters.
    050         * @param t current value of the independent <I>time</I> variable
    051         * @param primary array containing the current value of the primary state vector
    052         * @param primaryDot array containing the derivative of the primary state vector
    053         * @param secondary array containing the current value of the secondary state vector
    054         * @param secondaryDot placeholder array where to put the derivative of the secondary state vector
    055         * @exception MaxCountExceededException if the number of functions evaluations is exceeded
    056         * @exception DimensionMismatchException if arrays dimensions do not match equations settings
    057         */
    058        void computeDerivatives(double t, double[] primary, double[] primaryDot,
    059                                double[] secondary, double[] secondaryDot)
    060            throws MaxCountExceededException, DimensionMismatchException;
    061
    062    }