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18 package org.apache.commons.math.ode.nonstiff;
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20 import org.apache.commons.math.ode.DerivativeException;
21 import org.apache.commons.math.ode.sampling.AbstractStepInterpolator;
22 import org.apache.commons.math.ode.sampling.StepInterpolator;
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34 class HighamHall54StepInterpolator
35 extends RungeKuttaStepInterpolator {
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46 public HighamHall54StepInterpolator() {
47 super();
48 }
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55 public HighamHall54StepInterpolator(final HighamHall54StepInterpolator interpolator) {
56 super(interpolator);
57 }
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60 @Override
61 protected StepInterpolator doCopy() {
62 return new HighamHall54StepInterpolator(this);
63 }
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67 @Override
68 protected void computeInterpolatedStateAndDerivatives(final double theta,
69 final double oneMinusThetaH)
70 throws DerivativeException {
71
72 final double theta2 = theta * theta;
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74 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))));
75 final double b2 = h * (-27.0/32.0 + theta2 * (459.0/32.0 + theta * (-243.0/8.0 + theta * 135.0/8.0)));
76 final double b3 = h * (4.0/3.0 + theta2 * (-22.0 + theta * (152.0/3.0 + theta * -30.0)));
77 final double b4 = h * (-125.0/96.0 + theta2 * (375.0/32.0 + theta * (-625.0/24.0 + theta * 125.0/8.0)));
78 final double b5 = h * (-5.0/48.0 + theta2 * (-5.0/16.0 + theta * 5.0/12.0));
79 final double bDot0 = 1 + theta * (-15.0/2.0 + theta * (16.0 - 10.0 * theta));
80 final double bDot2 = theta * (459.0/16.0 + theta * (-729.0/8.0 + 135.0/2.0 * theta));
81 final double bDot3 = theta * (-44.0 + theta * (152.0 - 120.0 * theta));
82 final double bDot4 = theta * (375.0/16.0 + theta * (-625.0/8.0 + 125.0/2.0 * theta));
83 final double bDot5 = theta * 5.0/8.0 * (2 * theta - 1);
84
85 for (int i = 0; i < interpolatedState.length; ++i) {
86 final double yDot0 = yDotK[0][i];
87 final double yDot2 = yDotK[2][i];
88 final double yDot3 = yDotK[3][i];
89 final double yDot4 = yDotK[4][i];
90 final double yDot5 = yDotK[5][i];
91 interpolatedState[i] =
92 currentState[i] + b0 * yDot0 + b2 * yDot2 + b3 * yDot3 + b4 * yDot4 + b5 * yDot5;
93 interpolatedDerivatives[i] =
94 bDot0 * yDot0 + bDot2 * yDot2 + bDot3 * yDot3 + bDot4 * yDot4 + bDot5 * yDot5;
95 }
96
97 }
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100 private static final long serialVersionUID = -3583240427587318654L;
101
102 }