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 }