org.apache.commons.math3.ode.nonstiff.RungeKuttaFieldStepInterpolator Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of virtdata-lib-realer Show documentation
Show all versions of virtdata-lib-realer Show documentation
With inspiration from other libraries
/*
* 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.nonstiff;
import org.apache.commons.math3.Field;
import org.apache.commons.math3.RealFieldElement;
import org.apache.commons.math3.ode.FieldEquationsMapper;
import org.apache.commons.math3.ode.FieldODEStateAndDerivative;
import org.apache.commons.math3.ode.sampling.AbstractFieldStepInterpolator;
import org.apache.commons.math3.util.MathArrays;
/** This class represents an interpolator over the last step during an
* ODE integration for Runge-Kutta and embedded Runge-Kutta integrators.
*
* @see RungeKuttaFieldIntegrator
* @see EmbeddedRungeKuttaFieldIntegrator
*
* @param the type of the field elements
* @since 3.6
*/
abstract class RungeKuttaFieldStepInterpolator>
extends AbstractFieldStepInterpolator {
/** Field to which the time and state vector elements belong. */
private final Field field;
/** Slopes at the intermediate points. */
private final T[][] yDotK;
/** 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
*/
protected RungeKuttaFieldStepInterpolator(final Field field, final boolean forward,
final T[][] yDotK,
final FieldODEStateAndDerivative globalPreviousState,
final FieldODEStateAndDerivative globalCurrentState,
final FieldODEStateAndDerivative softPreviousState,
final FieldODEStateAndDerivative softCurrentState,
final FieldEquationsMapper mapper) {
super(forward, globalPreviousState, globalCurrentState, softPreviousState, softCurrentState, mapper);
this.field = field;
this.yDotK = MathArrays.buildArray(field, yDotK.length, -1);
for (int i = 0; i < yDotK.length; ++i) {
this.yDotK[i] = yDotK[i].clone();
}
}
/** {@inheritDoc} */
@Override
protected RungeKuttaFieldStepInterpolator create(boolean newForward,
FieldODEStateAndDerivative newGlobalPreviousState,
FieldODEStateAndDerivative newGlobalCurrentState,
FieldODEStateAndDerivative newSoftPreviousState,
FieldODEStateAndDerivative newSoftCurrentState,
FieldEquationsMapper newMapper) {
return create(field, newForward, yDotK,
newGlobalPreviousState, newGlobalCurrentState,
newSoftPreviousState, newSoftCurrentState,
newMapper);
}
/** Create a new instance.
* @param newField field to which the time and state vector elements belong
* @param newForward integration direction indicator
* @param newYDotK slopes at the intermediate points
* @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 RungeKuttaFieldStepInterpolator create(Field newField, boolean newForward, T[][] newYDotK,
FieldODEStateAndDerivative newGlobalPreviousState,
FieldODEStateAndDerivative newGlobalCurrentState,
FieldODEStateAndDerivative newSoftPreviousState,
FieldODEStateAndDerivative newSoftCurrentState,
FieldEquationsMapper newMapper);
/** Compute a state by linear combination added to previous state.
* @param coefficients coefficients to apply to the method staged derivatives
* @return combined state
*/
protected final T[] previousStateLinearCombination(final T ... coefficients) {
return combine(getPreviousState().getState(),
coefficients);
}
/** Compute a state by linear combination added to current state.
* @param coefficients coefficients to apply to the method staged derivatives
* @return combined state
*/
protected T[] currentStateLinearCombination(final T ... coefficients) {
return combine(getCurrentState().getState(),
coefficients);
}
/** Compute a state derivative by linear combination.
* @param coefficients coefficients to apply to the method staged derivatives
* @return combined state
*/
protected T[] derivativeLinearCombination(final T ... coefficients) {
return combine(MathArrays.buildArray(field, yDotK[0].length), coefficients);
}
/** Linearly combine arrays.
* @param a array to add to
* @param coefficients coefficients to apply to the method staged derivatives
* @return a itself, as a convenience for fluent API
*/
private T[] combine(final T[] a, final T ... coefficients) {
for (int i = 0; i < a.length; ++i) {
for (int k = 0; k < coefficients.length; ++k) {
a[i] = a[i].add(coefficients[k].multiply(yDotK[k][i]));
}
}
return a;
}
}