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
18 package org.apache.commons.math.ode;
19
20
21 /** This interface represents a first order differential equations set.
22 *
23 * <p>This interface should be implemented by all real first order
24 * differential equation problems before they can be handled by the
25 * integrators {@link FirstOrderIntegrator#integrate} method.</p>
26 *
27 * <p>A first order differential equations problem, as seen by an
28 * integrator is the time derivative <code>dY/dt</code> of a state
29 * vector <code>Y</code>, both being one dimensional arrays. From the
30 * integrator point of view, this derivative depends only on the
31 * current time <code>t</code> and on the state vector
32 * <code>Y</code>.</p>
33 *
34 * <p>For real problems, the derivative depends also on parameters
35 * that do not belong to the state vector (dynamical model constants
36 * for example). These constants are completely outside of the scope
37 * of this interface, the classes that implement it are allowed to
38 * handle them as they want.</p>
39 *
40 * @see FirstOrderIntegrator
41 * @see FirstOrderConverter
42 * @see SecondOrderDifferentialEquations
43 *
44 * @version $Revision: 786881 $ $Date: 2009-06-20 14:53:08 -0400 (Sat, 20 Jun 2009) $
45 * @since 1.2
46 */
47
48 public interface FirstOrderDifferentialEquations {
49
50 /** Get the dimension of the problem.
51 * @return dimension of the problem
52 */
53 public int getDimension();
54
55 /** Get the current time derivative of the state vector.
56 * @param t current value of the independent <I>time</I> variable
57 * @param y array containing the current value of the state vector
58 * @param yDot placeholder array where to put the time derivative of the state vector
59 * @throws DerivativeException this exception is propagated to the caller if the
60 * underlying user function triggers one
61 */
62 public void computeDerivatives(double t, double[] y, double[] yDot)
63 throws DerivativeException;
64
65 }