001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018package org.apache.commons.math3.ode;
019
020import org.apache.commons.math3.Field;
021import org.apache.commons.math3.RealFieldElement;
022import org.apache.commons.math3.util.MathArrays;
023
024/** Container for time, main and secondary state vectors.
025
026 * @see FirstOrderFieldDifferentialEquations
027 * @see FieldSecondaryEquations
028 * @see FirstOrderFieldIntegrator
029 * @see FieldODEStateAndDerivative
030 * @param <T> the type of the field elements
031 * @since 3.6
032 */
033
034public class FieldODEState<T extends RealFieldElement<T>> {
035
036    /** Time. */
037    private final T time;
038
039    /** Main state at time. */
040    private final T[] state;
041
042    /** Secondary state at time. */
043    private final T[][] secondaryState;
044
045    /** Simple constructor.
046     * <p>Calling this constructor is equivalent to call {@link
047     * #FieldODEState(RealFieldElement, RealFieldElement[], RealFieldElement[][])
048     * FieldODEState(time, state, null)}.</p>
049     * @param time time
050     * @param state state at time
051     */
052    public FieldODEState(T time, T[] state) {
053        this(time, state, null);
054    }
055
056    /** Simple constructor.
057     * @param time time
058     * @param state state at time
059     * @param secondaryState state at time (may be null)
060     */
061    public FieldODEState(T time, T[] state, T[][] secondaryState) {
062        this.time           = time;
063        this.state          = state.clone();
064        this.secondaryState = copy(time.getField(), secondaryState);
065    }
066
067    /** Copy a two-dimensions array.
068     * @param field field to which elements belong
069     * @param original original array (may be null)
070     * @return copied array or null if original array was null
071     */
072    protected T[][] copy(final Field<T> field, final T[][] original) {
073
074        // special handling of null arrays
075        if (original == null) {
076            return null;
077        }
078
079        // allocate the array
080        final T[][] copied = MathArrays.buildArray(field, original.length, -1);
081
082        // copy content
083        for (int i = 0; i < original.length; ++i) {
084            copied[i] = original[i].clone();
085        }
086
087        return copied;
088
089    }
090
091    /** Get time.
092     * @return time
093     */
094    public T getTime() {
095        return time;
096    }
097
098    /** Get main state dimension.
099     * @return main state dimension
100     */
101    public int getStateDimension() {
102        return state.length;
103    }
104
105    /** Get main state at time.
106     * @return main state at time
107     */
108    public T[] getState() {
109        return state.clone();
110    }
111
112    /** Get the number of secondary states.
113     * @return number of secondary states.
114     */
115    public int getNumberOfSecondaryStates() {
116        return secondaryState == null ? 0 : secondaryState.length;
117    }
118
119    /** Get secondary state dimension.
120     * @param index index of the secondary set as returned
121     * by {@link FieldExpandableODE#addSecondaryEquations(FieldSecondaryEquations)}
122     * (beware index 0 corresponds to main state, additional states start at 1)
123     * @return secondary state dimension
124     */
125    public int getSecondaryStateDimension(final int index) {
126        return index == 0 ? state.length : secondaryState[index - 1].length;
127    }
128
129    /** Get secondary state at time.
130     * @param index index of the secondary set as returned
131     * by {@link FieldExpandableODE#addSecondaryEquations(FieldSecondaryEquations)}
132     * (beware index 0 corresponds to main state, additional states start at 1)
133     * @return secondary state at time
134     */
135    public T[] getSecondaryState(final int index) {
136        return index == 0 ? state.clone() : secondaryState[index - 1].clone();
137    }
138
139}