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.math4.legacy.ode;
19
20 import org.apache.commons.math4.legacy.exception.DimensionMismatchException;
21 import org.apache.commons.math4.legacy.exception.MaxCountExceededException;
22
23
24
25 /** This interface represents a first order differential equations set.
26 *
27 * <p>This interface should be implemented by all real first order
28 * differential equation problems before they can be handled by the
29 * integrators {@link FirstOrderIntegrator#integrate} method.</p>
30 *
31 * <p>A first order differential equations problem, as seen by an
32 * integrator is the time derivative <code>dY/dt</code> of a state
33 * vector <code>Y</code>, both being one dimensional arrays. From the
34 * integrator point of view, this derivative depends only on the
35 * current time <code>t</code> and on the state vector
36 * <code>Y</code>.</p>
37 *
38 * <p>For real problems, the derivative depends also on parameters
39 * that do not belong to the state vector (dynamical model constants
40 * for example). These constants are completely outside of the scope
41 * of this interface, the classes that implement it are allowed to
42 * handle them as they want.</p>
43 *
44 * @see FirstOrderIntegrator
45 * @see FirstOrderConverter
46 * @see SecondOrderDifferentialEquations
47 *
48 * @since 1.2
49 */
50
51 public interface FirstOrderDifferentialEquations {
52
53 /** Get the dimension of the problem.
54 * @return dimension of the problem
55 */
56 int getDimension();
57
58 /** Get the current time derivative of the state vector.
59 * @param t current value of the independent <I>time</I> variable
60 * @param y array containing the current value of the state vector
61 * @param yDot placeholder array where to put the time derivative of the state vector
62 * @exception MaxCountExceededException if the number of functions evaluations is exceeded
63 * @exception DimensionMismatchException if arrays dimensions do not match equations settings
64 */
65 void computeDerivatives(double t, double[] y, double[] yDot)
66 throws MaxCountExceededException, DimensionMismatchException;
67 }