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18 package org.apache.commons.math4.legacy.ode;
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20 import org.apache.commons.math4.legacy.core.Field;
21 import org.apache.commons.math4.legacy.core.RealFieldElement;
22 import org.apache.commons.math4.legacy.core.MathArrays;
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39 public class TestFieldProblem1<T extends RealFieldElement<T>>
40 extends TestFieldProblemAbstract<T> {
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46 public TestFieldProblem1(Field<T> field) {
47 super(field);
48 setInitialConditions(convert(0.0), convert(1.0, 0.1));
49 setFinalConditions(convert(4.0));
50 setErrorScale(convert(1.0, 1.0));
51 }
52
53 @Override
54 public T[] doComputeDerivatives(T t, T[] y) {
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56 final T[] yDot = MathArrays.buildArray(getField(), getDimension());
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58
59 for (int i = 0; i < getDimension(); ++i) {
60 yDot[i] = y[i].negate();
61 }
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63 return yDot;
64 }
65
66 @Override
67 public T[] computeTheoreticalState(T t) {
68 final FieldODEState<T> s0 = getInitialState();
69 final T[] y0 = s0.getState();
70 final T[] y = MathArrays.buildArray(getField(), getDimension());
71 T c = s0.getTime().subtract(t).exp();
72 for (int i = 0; i < getDimension(); ++i) {
73 y[i] = c.multiply(y0[i]);
74 }
75 return y;
76 }
77 }