HighamHall54FieldStepInterpolator.java
/*
* 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,
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* See the License for the specific language governing permissions and
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package org.apache.commons.math4.legacy.ode.nonstiff;
import org.apache.commons.math4.legacy.core.Field;
import org.apache.commons.math4.legacy.core.RealFieldElement;
import org.apache.commons.math4.legacy.ode.FieldEquationsMapper;
import org.apache.commons.math4.legacy.ode.FieldODEStateAndDerivative;
/**
* This class represents an interpolator over the last step during an
* ODE integration for the 5(4) Higham and Hall integrator.
*
* @see HighamHall54FieldIntegrator
*
* @param <T> the type of the field elements
* @since 3.6
*/
class HighamHall54FieldStepInterpolator<T extends RealFieldElement<T>>
extends RungeKuttaFieldStepInterpolator<T> {
/** Simple constructor.
* @param field field to which the time and state vector elements belong
* @param forward integration direction indicator
* @param yDotK slopes at the intermediate points
* @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 mapper equations mapper for the all equations
*/
HighamHall54FieldStepInterpolator(final Field<T> field, final boolean forward,
final T[][] yDotK,
final FieldODEStateAndDerivative<T> globalPreviousState,
final FieldODEStateAndDerivative<T> globalCurrentState,
final FieldODEStateAndDerivative<T> softPreviousState,
final FieldODEStateAndDerivative<T> softCurrentState,
final FieldEquationsMapper<T> mapper) {
super(field, forward, yDotK,
globalPreviousState, globalCurrentState, softPreviousState, softCurrentState,
mapper);
}
/** {@inheritDoc} */
@Override
protected HighamHall54FieldStepInterpolator<T> create(final Field<T> newField, final boolean newForward, final T[][] newYDotK,
final FieldODEStateAndDerivative<T> newGlobalPreviousState,
final FieldODEStateAndDerivative<T> newGlobalCurrentState,
final FieldODEStateAndDerivative<T> newSoftPreviousState,
final FieldODEStateAndDerivative<T> newSoftCurrentState,
final FieldEquationsMapper<T> newMapper) {
return new HighamHall54FieldStepInterpolator<>(newField, newForward, newYDotK,
newGlobalPreviousState, newGlobalCurrentState,
newSoftPreviousState, newSoftCurrentState,
newMapper);
}
/** {@inheritDoc} */
@SuppressWarnings("unchecked")
@Override
protected FieldODEStateAndDerivative<T> computeInterpolatedStateAndDerivatives(final FieldEquationsMapper<T> mapper,
final T time, final T theta,
final T thetaH, final T oneMinusThetaH) {
final T bDot0 = theta.multiply(theta.multiply(theta.multiply( -10.0 ).add( 16.0 )).add(-15.0 / 2.0)).add(1);
final T bDot1 = time.getField().getZero();
final T bDot2 = theta.multiply(theta.multiply(theta.multiply( 135.0 / 2.0).add(-729.0 / 8.0)).add(459.0 / 16.0));
final T bDot3 = theta.multiply(theta.multiply(theta.multiply(-120.0 ).add( 152.0 )).add(-44.0 ));
final T bDot4 = theta.multiply(theta.multiply(theta.multiply( 125.0 / 2.0).add(-625.0 / 8.0)).add(375.0 / 16.0));
final T bDot5 = theta.multiply( 5.0 / 8.0).multiply(theta.multiply(2).subtract(1));
final T[] interpolatedState;
final T[] interpolatedDerivatives;
if (getGlobalPreviousState() != null && theta.getReal() <= 0.5) {
final T b0 = thetaH.multiply(theta.multiply(theta.multiply(theta.multiply( -5.0 / 2.0).add( 16.0 / 3.0)).add(-15.0 / 4.0)).add(1));
final T b1 = time.getField().getZero();
final T b2 = thetaH.multiply(theta.multiply(theta.multiply(theta.multiply(135.0 / 8.0).add(-243.0 / 8.0)).add(459.0 / 32.0)));
final T b3 = thetaH.multiply(theta.multiply(theta.multiply(theta.multiply(-30.0 ).add( 152.0 / 3.0)).add(-22.0 )));
final T b4 = thetaH.multiply(theta.multiply(theta.multiply(theta.multiply(125.0 / 8.0).add(-625.0 / 24.0)).add(375.0 / 32.0)));
final T b5 = thetaH.multiply(theta.multiply(theta.multiply( 5.0 / 12.0 ).add( -5.0 / 16.0)));
interpolatedState = previousStateLinearCombination(b0, b1, b2, b3, b4, b5);
interpolatedDerivatives = derivativeLinearCombination(bDot0, bDot1, bDot2, bDot3, bDot4, bDot5);
} else {
final T theta2 = theta.multiply(theta);
final T h = thetaH.divide(theta);
final T b0 = h.multiply( theta.multiply(theta.multiply(theta.multiply(theta.multiply(-5.0 / 2.0).add( 16.0 / 3.0)).add( -15.0 / 4.0)).add( 1.0 )).add( -1.0 / 12.0));
final T b1 = time.getField().getZero();
final T b2 = h.multiply(theta2.multiply(theta.multiply(theta.multiply( 135.0 / 8.0 ).add(-243.0 / 8.0)).add(459.0 / 32.0)).add( -27.0 / 32.0));
final T b3 = h.multiply(theta2.multiply(theta.multiply(theta.multiply( -30.0 ).add( 152.0 / 3.0)).add(-22.0 )).add( 4.0 / 3.0));
final T b4 = h.multiply(theta2.multiply(theta.multiply(theta.multiply( 125.0 / 8.0 ).add(-625.0 / 24.0)).add(375.0 / 32.0)).add(-125.0 / 96.0));
final T b5 = h.multiply(theta2.multiply(theta.multiply( 5.0 / 12.0 ).add(-5.0 / 16.0)).add( -5.0 / 48.0));
interpolatedState = currentStateLinearCombination(b0, b1, b2, b3, b4, b5);
interpolatedDerivatives = derivativeLinearCombination(bDot0, bDot1, bDot2, bDot3, bDot4, bDot5);
}
return new FieldODEStateAndDerivative<>(time, interpolatedState, interpolatedDerivatives);
}
}