1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache License, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 */ 17 18 package org.apache.commons.math.ode.nonstiff; 19 20 import org.apache.commons.math.ode.DerivativeException; 21 import org.apache.commons.math.ode.sampling.StepInterpolator; 22 23 /** 24 * This class represents an interpolator over the last step during an 25 * ODE integration for the 5(4) Higham and Hall integrator. 26 * 27 * @see HighamHall54Integrator 28 * 29 * @version $Revision: 1073158 $ $Date: 2011-02-21 22:46:52 +0100 (lun. 21 fvr. 2011) $ 30 * @since 1.2 31 */ 32 33 class HighamHall54StepInterpolator 34 extends RungeKuttaStepInterpolator { 35 36 /** Serializable version identifier */ 37 private static final long serialVersionUID = -3583240427587318654L; 38 39 /** Simple constructor. 40 * This constructor builds an instance that is not usable yet, the 41 * {@link 42 * org.apache.commons.math.ode.sampling.AbstractStepInterpolator#reinitialize} 43 * method should be called before using the instance in order to 44 * initialize the internal arrays. This constructor is used only 45 * in order to delay the initialization in some cases. The {@link 46 * EmbeddedRungeKuttaIntegrator} uses the prototyping design pattern 47 * to create the step interpolators by cloning an uninitialized model 48 * and later initializing the copy. 49 */ 50 public HighamHall54StepInterpolator() { 51 super(); 52 } 53 54 /** Copy constructor. 55 * @param interpolator interpolator to copy from. The copy is a deep 56 * copy: its arrays are separated from the original arrays of the 57 * instance 58 */ 59 public HighamHall54StepInterpolator(final HighamHall54StepInterpolator interpolator) { 60 super(interpolator); 61 } 62 63 /** {@inheritDoc} */ 64 @Override 65 protected StepInterpolator doCopy() { 66 return new HighamHall54StepInterpolator(this); 67 } 68 69 70 /** {@inheritDoc} */ 71 @Override 72 protected void computeInterpolatedStateAndDerivatives(final double theta, 73 final double oneMinusThetaH) 74 throws DerivativeException { 75 76 final double theta2 = theta * theta; 77 78 final double b0 = h * (-1.0/12.0 + theta * (1.0 + theta * (-15.0/4.0 + theta * (16.0/3.0 + theta * -5.0/2.0)))); 79 final double b2 = h * (-27.0/32.0 + theta2 * (459.0/32.0 + theta * (-243.0/8.0 + theta * 135.0/8.0))); 80 final double b3 = h * (4.0/3.0 + theta2 * (-22.0 + theta * (152.0/3.0 + theta * -30.0))); 81 final double b4 = h * (-125.0/96.0 + theta2 * (375.0/32.0 + theta * (-625.0/24.0 + theta * 125.0/8.0))); 82 final double b5 = h * (-5.0/48.0 + theta2 * (-5.0/16.0 + theta * 5.0/12.0)); 83 final double bDot0 = 1 + theta * (-15.0/2.0 + theta * (16.0 - 10.0 * theta)); 84 final double bDot2 = theta * (459.0/16.0 + theta * (-729.0/8.0 + 135.0/2.0 * theta)); 85 final double bDot3 = theta * (-44.0 + theta * (152.0 - 120.0 * theta)); 86 final double bDot4 = theta * (375.0/16.0 + theta * (-625.0/8.0 + 125.0/2.0 * theta)); 87 final double bDot5 = theta * 5.0/8.0 * (2 * theta - 1); 88 89 for (int i = 0; i < interpolatedState.length; ++i) { 90 final double yDot0 = yDotK[0][i]; 91 final double yDot2 = yDotK[2][i]; 92 final double yDot3 = yDotK[3][i]; 93 final double yDot4 = yDotK[4][i]; 94 final double yDot5 = yDotK[5][i]; 95 interpolatedState[i] = 96 currentState[i] + b0 * yDot0 + b2 * yDot2 + b3 * yDot3 + b4 * yDot4 + b5 * yDot5; 97 interpolatedDerivatives[i] = 98 bDot0 * yDot0 + bDot2 * yDot2 + bDot3 * yDot3 + bDot4 * yDot4 + bDot5 * yDot5; 99 } 100 101 } 102 103 } 104
