1/*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements.  See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License.  You may obtain a copy of the License at
8 *
9 *      http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18package org.apache.commons.math.ode;
19
20
21
22/** This interface represents a first order differential equations set.
23 *
24 * <p>This interface should be implemented by all real first order
25 * differential equation problems before they can be handled by the
26 * integrators {@link FirstOrderIntegrator#integrate} method.</p>
27 *
28 * <p>A first order differential equations problem, as seen by an
29 * integrator is the time derivative <code>dY/dt</code> of a state
30 * vector <code>Y</code>, both being one dimensional arrays. From the
31 * integrator point of view, this derivative depends only on the
32 * current time <code>t</code> and on the state vector
33 * <code>Y</code>.</p>
34 *
35 * <p>For real problems, the derivative depends also on parameters
36 * that do not belong to the state vector (dynamical model constants
37 * for example). These constants are completely outside of the scope
38 * of this interface, the classes that implement it are allowed to
39 * handle them as they want.</p>
40 *
41 * @see FirstOrderIntegrator
42 * @see FirstOrderConverter
43 * @see SecondOrderDifferentialEquations
44 *
45 * @version $Revision: 1073158 $ $Date: 2011-02-21 22:46:52 +0100 (lun. 21 févr. 2011) $
46 * @since 1.2
47 */
48
49public interface FirstOrderDifferentialEquations {
50
51    /** Get the dimension of the problem.
52     * @return dimension of the problem
53     */
54    int getDimension();
55
56    /** Get the current time derivative of the state vector.
57     * @param t current value of the independent <I>time</I> variable
58     * @param y array containing the current value of the state vector
59     * @param yDot placeholder array where to put the time derivative of the state vector
60     * @throws DerivativeException this user-defined exception should be used if an error is
61     * is triggered by user code
62     */
63    void computeDerivatives(double t, double[] y, double[] yDot)
64        throws DerivativeException;
65
66}
67