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 * https://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 /*
19 * This is not the original file distributed by the Apache Software Foundation
20 * It has been modified by the Hipparchus project
21 */
22
23 package org.hipparchus.migration.ode;
24
25 import org.hipparchus.ode.SecondOrderODE;
26
27 /** This interface represents a second order differential equations set.
28
29 * <p>This interface should be implemented by all real second order
30 * differential equation problems before they can be handled by the
31 * {@link org.hipparchus.ode.FirstOrderConverter converter to first order}.</p>
32 *
33 * <p>A second order differential equations problem, as seen by an
34 * integrator is the second time derivative <code>d2Y/dt^2</code> of a
35 * state vector <code>Y</code>, both being one dimensional
36 * arrays. From the integrator point of view, this derivative depends
37 * only on the current time <code>t</code>, on the state vector
38 * <code>Y</code> and on the first time derivative of the state
39 * vector.</p>
40 *
41 * <p>For real problems, the derivative depends also on parameters
42 * that do not belong to the state vector (dynamical model constants
43 * for example). These constants are completely outside of the scope
44 * of this interface, the classes that implement it are allowed to
45 * handle them as they want.</p>
46 * @deprecated as of 1.0, replaced with {@link SecondOrderODE}
47 */
48 @Deprecated
49 public interface SecondOrderDifferentialEquations extends SecondOrderODE {
50
51 /** {@inheritDoc} */
52 @Override
53 default double[] computeSecondDerivatives(double t, double[] y, double[] yDot) {
54 final double[] yDDot = new double[y.length];
55 computeSecondDerivatives(t, y, yDot, yDDot);
56 return yDDot;
57 }
58
59 /** Get the current time derivative of the state vector.
60 * @param t current value of the independent <I>time</I> variable
61 * @param y array containing the current value of the state vector
62 * @param yDot array containing the current value of the first derivative
63 * of the state vector
64 * @param yDDot placeholder array where to put the second time derivative
65 * of the state vector
66 */
67 void computeSecondDerivatives(double t, double[] y, double[] yDot, double[] yDDot);
68
69 }