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.core.RealFieldElement;
21 import org.apache.commons.math4.legacy.exception.DimensionMismatchException;
22 import org.apache.commons.math4.legacy.exception.MaxCountExceededException;
23
24 /**
25 * This interface allows users to add secondary differential equations to a primary
26 * set of differential equations.
27 * <p>
28 * In some cases users may need to integrate some problem-specific equations along
29 * with a primary set of differential equations. One example is optimal control where
30 * adjoined parameters linked to the minimized Hamiltonian must be integrated.
31 * </p>
32 * <p>
33 * This interface allows users to add such equations to a primary set of {@link
34 * FirstOrderFieldDifferentialEquations first order differential equations}
35 * thanks to the {@link FieldExpandableODE#addSecondaryEquations(FieldSecondaryEquations)}
36 * method.
37 * </p>
38 * @see FirstOrderFieldDifferentialEquations
39 * @see FieldExpandableODE
40 * @param <T> the type of the field elements
41 * @since 3.6
42 */
43 public interface FieldSecondaryEquations<T extends RealFieldElement<T>> {
44
45 /** Get the dimension of the secondary state parameters.
46 * @return dimension of the secondary state parameters
47 */
48 int getDimension();
49
50 /** Initialize equations at the start of an ODE integration.
51 * <p>
52 * This method is called once at the start of the integration. It
53 * may be used by the equations to initialize some internal data
54 * if needed.
55 * </p>
56 * @param t0 value of the independent <I>time</I> variable at integration start
57 * @param primary0 array containing the value of the primary state vector at integration start
58 * @param secondary0 array containing the value of the secondary state vector at integration start
59 * @param finalTime target time for the integration
60 */
61 void init(T t0, T[] primary0, T[] secondary0, T finalTime);
62
63 /** Compute the derivatives related to the secondary state parameters.
64 * @param t current value of the independent <I>time</I> variable
65 * @param primary array containing the current value of the primary state vector
66 * @param primaryDot array containing the derivative of the primary state vector
67 * @param secondary array containing the current value of the secondary state vector
68 * @return derivative of the secondary state vector
69 * @exception MaxCountExceededException if the number of functions evaluations is exceeded
70 * @exception DimensionMismatchException if arrays dimensions do not match equations settings
71 */
72 T[] computeDerivatives(T t, T[] primary, T[] primaryDot, T[] secondary)
73 throws MaxCountExceededException, DimensionMismatchException;
74 }