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    }