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Java example source code file (AbstractFieldStepInterpolator.java)

This example Java source code file (AbstractFieldStepInterpolator.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.

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Java - Java tags/keywords

abstractfieldstepinterpolator, fieldequationsmapper, fieldodestateandderivative, maxcountexceededexception, realfieldelement

The AbstractFieldStepInterpolator.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,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.commons.math3.ode.sampling;

import org.apache.commons.math3.RealFieldElement;
import org.apache.commons.math3.exception.MaxCountExceededException;
import org.apache.commons.math3.ode.FieldEquationsMapper;
import org.apache.commons.math3.ode.FieldODEStateAndDerivative;

/** This abstract class represents an interpolator over the last step
 * during an ODE integration.
 *
 * <p>The various ODE integrators provide objects extending this class
 * to the step handlers. The handlers can use these objects to
 * retrieve the state vector at intermediate times between the
 * previous and the current grid points (dense output).</p>
 *
 * @see org.apache.commons.math3.ode.FirstOrderFieldIntegrator
 * @see StepHandler
 *
 * @param <T> the type of the field elements
 * @since 3.6
 */

public abstract class AbstractFieldStepInterpolator<T extends RealFieldElement
    implements FieldStepInterpolator<T> {

    /** Global previous state. */
    private final FieldODEStateAndDerivative<T> globalPreviousState;

    /** Global current state. */
    private final FieldODEStateAndDerivative<T> globalCurrentState;

    /** Soft previous state. */
    private final FieldODEStateAndDerivative<T> softPreviousState;

    /** Soft current state. */
    private final FieldODEStateAndDerivative<T> softCurrentState;

    /** integration direction. */
    private final boolean forward;

    /** Mapper for ODE equations primary and secondary components. */
    private FieldEquationsMapper<T> mapper;

    /** Simple constructor.
     * @param isForward integration direction indicator
     * @param globalPreviousState start of the global step
     * @param globalCurrentState end of the global step
     * @param softPreviousState start of the restricted step
     * @param softCurrentState end of the restricted step
     * @param equationsMapper mapper for ODE equations primary and secondary components
     */
    protected AbstractFieldStepInterpolator(final boolean isForward,
                                            final FieldODEStateAndDerivative<T> globalPreviousState,
                                            final FieldODEStateAndDerivative<T> globalCurrentState,
                                            final FieldODEStateAndDerivative<T> softPreviousState,
                                            final FieldODEStateAndDerivative<T> softCurrentState,
                                            final FieldEquationsMapper<T> equationsMapper) {
        this.forward             = isForward;
        this.globalPreviousState = globalPreviousState;
        this.globalCurrentState  = globalCurrentState;
        this.softPreviousState   = softPreviousState;
        this.softCurrentState    = softCurrentState;
        this.mapper              = equationsMapper;
    }

    /** Create a new restricted version of the instance.
     * <p>
     * The instance is not changed at all.
     * </p>
     * @param previousState start of the restricted step
     * @param currentState end of the restricted step
     * @return restricted version of the instance
     * @see #getPreviousState()
     * @see #getCurrentState()
     */
    public AbstractFieldStepInterpolator<T> restrictStep(final FieldODEStateAndDerivative previousState,
                                                         final FieldODEStateAndDerivative<T> currentState) {
        return create(forward, globalPreviousState, globalCurrentState, previousState, currentState, mapper);
    }

    /** Create a new instance.
     * @param newForward integration direction indicator
     * @param newGlobalPreviousState start of the global step
     * @param newGlobalCurrentState end of the global step
     * @param newSoftPreviousState start of the restricted step
     * @param newSoftCurrentState end of the restricted step
     * @param newMapper equations mapper for the all equations
     * @return a new instance
     */
    protected abstract AbstractFieldStepInterpolator<T> create(boolean newForward,
                                                               FieldODEStateAndDerivative<T> newGlobalPreviousState,
                                                               FieldODEStateAndDerivative<T> newGlobalCurrentState,
                                                               FieldODEStateAndDerivative<T> newSoftPreviousState,
                                                               FieldODEStateAndDerivative<T> newSoftCurrentState,
                                                               FieldEquationsMapper<T> newMapper);

    /**
     * Get the previous global grid point state.
     * @return previous global grid point state
     */
    public FieldODEStateAndDerivative<T> getGlobalPreviousState() {
        return globalPreviousState;
    }

    /**
     * Get the current global grid point state.
     * @return current global grid point state
     */
    public FieldODEStateAndDerivative<T> getGlobalCurrentState() {
        return globalCurrentState;
    }

    /** {@inheritDoc} */
    public FieldODEStateAndDerivative<T> getPreviousState() {
        return softPreviousState;
    }

    /** {@inheritDoc} */
    public FieldODEStateAndDerivative<T> getCurrentState() {
        return softCurrentState;
    }

    /** {@inheritDoc} */
    public FieldODEStateAndDerivative<T> getInterpolatedState(final T time) {
        final T thetaH         = time.subtract(globalPreviousState.getTime());
        final T oneMinusThetaH = globalCurrentState.getTime().subtract(time);
        final T theta          = thetaH.divide(globalCurrentState.getTime().subtract(globalPreviousState.getTime()));
        return computeInterpolatedStateAndDerivatives(mapper, time, theta, thetaH, oneMinusThetaH);
    }

    /** {@inheritDoc} */
    public boolean isForward() {
        return forward;
    }

    /** Compute the state and derivatives at the interpolated time.
     * This is the main processing method that should be implemented by
     * the derived classes to perform the interpolation.
     * @param equationsMapper mapper for ODE equations primary and secondary components
     * @param time interpolation time
     * @param theta normalized interpolation abscissa within the step
     * (theta is zero at the previous time step and one at the current time step)
     * @param thetaH time gap between the previous time and the interpolated time
     * @param oneMinusThetaH time gap between the interpolated time and
     * the current time
     * @return interpolated state and derivatives
     * @exception MaxCountExceededException if the number of functions evaluations is exceeded
     */
    protected abstract FieldODEStateAndDerivative<T> computeInterpolatedStateAndDerivatives(FieldEquationsMapper equationsMapper,
                                                                                            T time, T theta,
                                                                                            T thetaH, T oneMinusThetaH)
        throws MaxCountExceededException;

}

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