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.Field;
21 import org.apache.commons.math4.legacy.core.RealFieldElement;
22 import org.apache.commons.math4.legacy.core.MathArrays;
23
24 /** Container for time, main and secondary state vectors.
25
26 * @see FirstOrderFieldDifferentialEquations
27 * @see FieldSecondaryEquations
28 * @see FirstOrderFieldIntegrator
29 * @see FieldODEStateAndDerivative
30 * @param <T> the type of the field elements
31 * @since 3.6
32 */
33
34 public class FieldODEState<T extends RealFieldElement<T>> {
35
36 /** Time. */
37 private final T time;
38
39 /** Main state at time. */
40 private final T[] state;
41
42 /** Secondary state at time. */
43 private final T[][] secondaryState;
44
45 /** Simple constructor.
46 * <p>Calling this constructor is equivalent to call {@link
47 * #FieldODEState(RealFieldElement, RealFieldElement[], RealFieldElement[][])
48 * FieldODEState(time, state, null)}.</p>
49 * @param time time
50 * @param state state at time
51 */
52 public FieldODEState(T time, T[] state) {
53 this(time, state, null);
54 }
55
56 /** Simple constructor.
57 * @param time time
58 * @param state state at time
59 * @param secondaryState state at time (may be null)
60 */
61 public FieldODEState(T time, T[] state, T[][] secondaryState) {
62 this.time = time;
63 this.state = state.clone();
64 this.secondaryState = copy(time.getField(), secondaryState);
65 }
66
67 /** Copy a two-dimensions array.
68 * @param field field to which elements belong
69 * @param original original array (may be null)
70 * @return copied array or null if original array was null
71 */
72 protected T[][] copy(final Field<T> field, final T[][] original) {
73
74 // special handling of null arrays
75 if (original == null) {
76 return null;
77 }
78
79 // allocate the array
80 final T[][] copied = MathArrays.buildArray(field, original.length, -1);
81
82 // copy content
83 for (int i = 0; i < original.length; ++i) {
84 copied[i] = original[i].clone();
85 }
86
87 return copied;
88 }
89
90 /** Get time.
91 * @return time
92 */
93 public T getTime() {
94 return time;
95 }
96
97 /** Get main state dimension.
98 * @return main state dimension
99 */
100 public int getStateDimension() {
101 return state.length;
102 }
103
104 /** Get main state at time.
105 * @return main state at time
106 */
107 public T[] getState() {
108 return state.clone();
109 }
110
111 /** Get the number of secondary states.
112 * @return number of secondary states.
113 */
114 public int getNumberOfSecondaryStates() {
115 return secondaryState == null ? 0 : secondaryState.length;
116 }
117
118 /** Get secondary state dimension.
119 * @param index index of the secondary set as returned
120 * by {@link FieldExpandableODE#addSecondaryEquations(FieldSecondaryEquations)}
121 * (beware index 0 corresponds to main state, additional states start at 1)
122 * @return secondary state dimension
123 */
124 public int getSecondaryStateDimension(final int index) {
125 return index == 0 ? state.length : secondaryState[index - 1].length;
126 }
127
128 /** Get secondary state at time.
129 * @param index index of the secondary set as returned
130 * by {@link FieldExpandableODE#addSecondaryEquations(FieldSecondaryEquations)}
131 * (beware index 0 corresponds to main state, additional states start at 1)
132 * @return secondary state at time
133 */
134 public T[] getSecondaryState(final int index) {
135 return index == 0 ? state.clone() : secondaryState[index - 1].clone();
136 }
137 }