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Java example source code file (FieldODEState.java)

This example Java source code file (FieldODEState.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

field, fieldodestate, realfieldelement

The FieldODEState.java Java example source code

 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *      http://www.apache.org/licenses/LICENSE-2.0
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * See the License for the specific language governing permissions and
 * limitations under the License.

package org.apache.commons.math3.ode;

import org.apache.commons.math3.Field;
import org.apache.commons.math3.RealFieldElement;
import org.apache.commons.math3.util.MathArrays;

/** Container for time, main and secondary state vectors.

 * @see FirstOrderFieldDifferentialEquations
 * @see FieldSecondaryEquations
 * @see FirstOrderFieldIntegrator
 * @see FieldODEStateAndDerivative
 * @param <T> the type of the field elements
 * @since 3.6

public class FieldODEState<T extends RealFieldElement {

    /** Time. */
    private final T time;

    /** Main state at time. */
    private final T[] state;

    /** Secondary state at time. */
    private final T[][] secondaryState;

    /** Simple constructor.
     * <p>Calling this constructor is equivalent to call {@link
     * #FieldODEState(RealFieldElement, RealFieldElement[], RealFieldElement[][])
     * FieldODEState(time, state, null)}.</p>
     * @param time time
     * @param state state at time
    public FieldODEState(T time, T[] state) {
        this(time, state, null);

    /** Simple constructor.
     * @param time time
     * @param state state at time
     * @param secondaryState state at time (may be null)
    public FieldODEState(T time, T[] state, T[][] secondaryState) {
        this.time           = time;
        this.state          = state.clone();
        this.secondaryState = copy(time.getField(), secondaryState);

    /** Copy a two-dimensions array.
     * @param field field to which elements belong
     * @param original original array (may be null)
     * @return copied array or null if original array was null
    protected T[][] copy(final Field<T> field, final T[][] original) {

        // special handling of null arrays
        if (original == null) {
            return null;

        // allocate the array
        final T[][] copied = MathArrays.buildArray(field, original.length, -1);

        // copy content
        for (int i = 0; i < original.length; ++i) {
            copied[i] = original[i].clone();

        return copied;


    /** Get time.
     * @return time
    public T getTime() {
        return time;

    /** Get main state dimension.
     * @return main state dimension
    public int getStateDimension() {
        return state.length;

    /** Get main state at time.
     * @return main state at time
    public T[] getState() {
        return state.clone();

    /** Get the number of secondary states.
     * @return number of secondary states.
    public int getNumberOfSecondaryStates() {
        return secondaryState == null ? 0 : secondaryState.length;

    /** Get secondary state dimension.
     * @param index index of the secondary set as returned
     * by {@link FieldExpandableODE#addSecondaryEquations(FieldSecondaryEquations)}
     * (beware index 0 corresponds to main state, additional states start at 1)
     * @return secondary state dimension
    public int getSecondaryStateDimension(final int index) {
        return index == 0 ? state.length : secondaryState[index - 1].length;

    /** Get secondary state at time.
     * @param index index of the secondary set as returned
     * by {@link FieldExpandableODE#addSecondaryEquations(FieldSecondaryEquations)}
     * (beware index 0 corresponds to main state, additional states start at 1)
     * @return secondary state at time
    public T[] getSecondaryState(final int index) {
        return index == 0 ? state.clone() : secondaryState[index - 1].clone();


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