Raymond | dee0849 | 2015-04-02 10:43:13 -0700 | [diff] [blame] | 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 févr. 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 | } |