    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.math.ode;
    018
    019
    020    /** This interface represents a first order differential equations set
    021     * with a main set of equations and an extension set.
    022     *
    023     * <p>
    024     * This interface is a simple extension on the {@link
    025     * FirstOrderDifferentialEquations} that allows to identify which part
    026     * of a complete set of differential equations correspond to the main
    027     * set and which part correspond to the extension set.
    028     * </p>
    029     * <p>
    030     * One typical use case is the computation of Jacobians. The main
    031     * set of equations correspond to the raw ode, and we add to this set
    032     * another bunch of equations which represent the jacobians of the
    033     * main set. In that case, we want the integrator to use <em>only</em>
    034     * the main set to estimate the errors and hence the step sizes. It should
    035     * <em>not</em> use the additional equations in this computation. If the
    036     * complete ode implements this interface, the {@link FirstOrderIntegrator
    037     * integrator} will be able to know where the main set ends and where the
    038     * extended set begins.
    039     * </p>
    040     * <p>
    041     * We consider that the main set always corresponds to the first equations
    042     * and the extended set to the last equations.
    043     * </p>
    044     *
    045     * @see FirstOrderDifferentialEquations
    046     *
    047     * @version $Revision: 980981 $ $Date: 2010-07-31 00:03:04 +0200 (sam. 31 juil. 2010) $
    048     * @since 2.2
    049     */
    050
    051    public interface ExtendedFirstOrderDifferentialEquations extends FirstOrderDifferentialEquations {
    052
    053        /** Return the dimension of the main set of equations.
    054         * <p>
    055         * The main set of equations represent the first part of an ODE state.
    056         * The error estimations and adaptive step size computation should be
    057         * done on this first part only, not on the final part of the state
    058         * which represent an extension set of equations which are considered
    059         * secondary.
    060         * </p>
    061         * @return dimension of the main set of equations, must be lesser than or
    062         * equal to the {@link #getDimension() total dimension}
    063         */
    064        int getMainSetDimension();
    065
    066    }