| /* |
| * 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.math4.ode.nonstiff; |
| |
| import org.apache.commons.math4.Field; |
| import org.apache.commons.math4.RealFieldElement; |
| import org.apache.commons.math4.ode.FieldEquationsMapper; |
| import org.apache.commons.math4.ode.FieldODEStateAndDerivative; |
| import org.apache.commons.math4.ode.sampling.AbstractFieldStepInterpolator; |
| import org.apache.commons.math4.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 <T> the type of the field elements |
| * @since 3.6 |
| */ |
| |
| abstract class RungeKuttaFieldStepInterpolator<T extends RealFieldElement<T>> |
| extends AbstractFieldStepInterpolator<T> { |
| |
| /** Field to which the time and state vector elements belong. */ |
| private final Field<T> 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<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(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<T> create(boolean newForward, |
| FieldODEStateAndDerivative<T> newGlobalPreviousState, |
| FieldODEStateAndDerivative<T> newGlobalCurrentState, |
| FieldODEStateAndDerivative<T> newSoftPreviousState, |
| FieldODEStateAndDerivative<T> newSoftCurrentState, |
| FieldEquationsMapper<T> 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<T> create(Field<T> newField, boolean newForward, T[][] newYDotK, |
| FieldODEStateAndDerivative<T> newGlobalPreviousState, |
| FieldODEStateAndDerivative<T> newGlobalCurrentState, |
| FieldODEStateAndDerivative<T> newSoftPreviousState, |
| FieldODEStateAndDerivative<T> newSoftCurrentState, |
| FieldEquationsMapper<T> newMapper); |
| |
| /** Compute a state by linear combination added to previous state. |
| * @param coefficients coefficients to apply to the method staged derivatives |
| * @return combined state |
| */ |
| @SafeVarargs |
| 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 |
| */ |
| @SuppressWarnings("unchecked") |
| 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 |
| */ |
| @SuppressWarnings("unchecked") |
| 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 |
| */ |
| @SuppressWarnings("unchecked") |
| 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; |
| } |
| |
| } |