Examples of TestProblem3

org.apache.commons.math.ode.TestProblem3
This class is used in the junit tests for the ODE integrators.
This specific problem is the following differential equation :
```
 y1'' = -y1/r^3  y1 (0) = 1-e  y1' (0) = 0 y2'' = -y2/r^3  y2 (0) = 0    y2' (0) =sqrt((1+e)/(1-e)) r = sqrt (y1^2 + y2^2), e = 0.9 
```
This is a two-body problem in the plane which can be solved by Kepler's equation
```
 y1 (t) = ... 
```
org.apache.commons.math3.ode.TestProblem3
This class is used in the junit tests for the ODE integrators.
This specific problem is the following differential equation :
```
 y1'' = -y1/r^3  y1 (0) = 1-e  y1' (0) = 0 y2'' = -y2/r^3  y2 (0) = 0    y2' (0) =sqrt((1+e)/(1-e)) r = sqrt (y1^2 + y2^2), e = 0.9 
```
This is a two-body problem in the plane which can be solved by Kepler's equation
```
 y1 (t) = ... 
```

Examples of org.apache.commons.math.ode.TestProblem3

public class GraggBulirschStoerStepInterpolatorTest {


  @Test
  public void derivativesConsistency()
  throws DerivativeException, IntegratorException {
    TestProblem3 pb = new TestProblem3(0.9);
    double minStep   = 0;
    double maxStep   = pb.getFinalTime() - pb.getInitialTime();
    double absTolerance = 1.0e-8;
    double relTolerance = 1.0e-8;


    GraggBulirschStoerIntegrator integ =
      new GraggBulirschStoerIntegrator(minStep, maxStep,

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Examples of org.apache.commons.math.ode.TestProblem3

  @Test
  public void serialization()
    throws DerivativeException, IntegratorException,
           IOException, ClassNotFoundException {


    TestProblem3 pb  = new TestProblem3(0.9);
    double minStep   = 0;
    double maxStep   = pb.getFinalTime() - pb.getInitialTime();
    double absTolerance = 1.0e-8;
    double relTolerance = 1.0e-8;


    GraggBulirschStoerIntegrator integ =
      new GraggBulirschStoerIntegrator(minStep, maxStep,
                                       absTolerance, relTolerance);
    integ.addStepHandler(new ContinuousOutputModel());
    integ.integrate(pb,
                    pb.getInitialTime(), pb.getInitialState(),
                    pb.getFinalTime(), new double[pb.getDimension()]);


    ByteArrayOutputStream bos = new ByteArrayOutputStream();
    ObjectOutputStream    oos = new ObjectOutputStream(bos);
    for (StepHandler handler : integ.getStepHandlers()) {
        oos.writeObject(handler);
    }


    assertTrue(bos.size () > 33000);
    assertTrue(bos.size () < 34000);


    ByteArrayInputStream  bis = new ByteArrayInputStream(bos.toByteArray());
    ObjectInputStream     ois = new ObjectInputStream(bis);
    ContinuousOutputModel cm  = (ContinuousOutputModel) ois.readObject();


    Random random = new Random(347588535632l);
    double maxError = 0.0;
    for (int i = 0; i < 1000; ++i) {
      double r = random.nextDouble();
      double time = r * pb.getInitialTime() + (1.0 - r) * pb.getFinalTime();
      cm.setInterpolatedTime(time);
      double[] interpolatedY = cm.getInterpolatedState ();
      double[] theoreticalY  = pb.computeTheoreticalState(time);
      double dx = interpolatedY[0] - theoreticalY[0];
      double dy = interpolatedY[1] - theoreticalY[1];
      double error = dx * dx + dy * dy;
      if (error > maxError) {
        maxError = error;

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Examples of org.apache.commons.math.ode.TestProblem3

  }


  @Test
  public void checklone()
  throws DerivativeException, IntegratorException {
    TestProblem3 pb = new TestProblem3(0.9);
    double minStep = 0;
    double maxStep = pb.getFinalTime() - pb.getInitialTime();
    double scalAbsoluteTolerance = 1.0e-8;
    double scalRelativeTolerance = scalAbsoluteTolerance;
    GraggBulirschStoerIntegrator integ = new GraggBulirschStoerIntegrator(minStep, maxStep,
                                                                          scalAbsoluteTolerance,
                                                                          scalRelativeTolerance);
    integ.addStepHandler(new StepHandler() {
        public void handleStep(StepInterpolator interpolator, boolean isLast)
        throws DerivativeException {
            StepInterpolator cloned = interpolator.copy();
            double tA = cloned.getPreviousTime();
            double tB = cloned.getCurrentTime();
            double halfStep = Math.abs(tB - tA) / 2;
            assertEquals(interpolator.getPreviousTime(), tA, 1.0e-12);
            assertEquals(interpolator.getCurrentTime(), tB, 1.0e-12);
            for (int i = 0; i < 10; ++i) {
                double t = (i * tB + (9 - i) * tA) / 9;
                interpolator.setInterpolatedTime(t);
                assertTrue(Math.abs(cloned.getInterpolatedTime() - t) > (halfStep / 10));
                cloned.setInterpolatedTime(t);
                assertEquals(t, cloned.getInterpolatedTime(), 1.0e-12);
                double[] referenceState = interpolator.getInterpolatedState();
                double[] cloneState     = cloned.getInterpolatedState();
                for (int j = 0; j < referenceState.length; ++j) {
                    assertEquals(referenceState[j], cloneState[j], 1.0e-12);
                }
            }
        }
        public boolean requiresDenseOutput() {
            return true;
        }
        public void reset() {
        }
    });
    integ.integrate(pb,
            pb.getInitialTime(), pb.getInitialState(),
            pb.getFinalTime(), new double[pb.getDimension()]);


  }

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Examples of org.apache.commons.math.ode.TestProblem3

    this.lastSeen = lastSeen;
  }


  @Override
  public void setUp() {
    pb = new TestProblem3(0.9);
    double minStep = 0;
    double maxStep = pb.getFinalTime() - pb.getInitialTime();
    integ = new DormandPrince54Integrator(minStep, maxStep, 10.e-8, 1.0e-8);
    lastSeen = false;
  }

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Examples of org.apache.commons.math.ode.TestProblem3

  }


  public void testKepler()
    throws DerivativeException, IntegratorException {


    final TestProblem3 pb  = new TestProblem3(0.9);
    double minStep = 0;
    double maxStep = pb.getFinalTime() - pb.getInitialTime();
    double scalAbsoluteTolerance = 1.0e-8;
    double scalRelativeTolerance = scalAbsoluteTolerance;


    FirstOrderIntegrator integ = new DormandPrince54Integrator(minStep, maxStep,
                                                               scalAbsoluteTolerance,
                                                               scalRelativeTolerance);
    integ.addStepHandler(new KeplerHandler(pb));
    integ.integrate(pb,
                    pb.getInitialTime(), pb.getInitialState(),
                    pb.getFinalTime(), new double[pb.getDimension()]);


    assertEquals(integ.getEvaluations(), pb.getCalls());
    assertTrue(pb.getCalls() < 2800);


  }

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Examples of org.apache.commons.math.ode.TestProblem3

  }


  public void testVariableSteps()
    throws DerivativeException, IntegratorException {


    final TestProblem3 pb  = new TestProblem3(0.9);
    double minStep = 0;
    double maxStep = pb.getFinalTime() - pb.getInitialTime();
    double scalAbsoluteTolerance = 1.0e-8;
    double scalRelativeTolerance = scalAbsoluteTolerance;


    FirstOrderIntegrator integ = new DormandPrince54Integrator(minStep, maxStep,
                                                               scalAbsoluteTolerance,
                                                               scalRelativeTolerance);
    integ.addStepHandler(new VariableHandler());
    double stopTime = integ.integrate(pb, pb.getInitialTime(), pb.getInitialState(),
                                      pb.getFinalTime(), new double[pb.getDimension()]);
    assertEquals(pb.getFinalTime(), stopTime, 1.0e-10);
  }

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Examples of org.apache.commons.math.ode.TestProblem3

  }


  public void testKepler()
    throws DerivativeException, IntegratorException {


    final TestProblem3 pb  = new TestProblem3(0.9);
    double minStep = 0;
    double maxStep = pb.getFinalTime() - pb.getInitialTime();
    double scalAbsoluteTolerance = 1.0e-8;
    double scalRelativeTolerance = scalAbsoluteTolerance;


    FirstOrderIntegrator integ = new DormandPrince853Integrator(minStep, maxStep,
                                                                scalAbsoluteTolerance,
                                                                scalRelativeTolerance);
    integ.addStepHandler(new KeplerHandler(pb));
    integ.integrate(pb,
                    pb.getInitialTime(), pb.getInitialState(),
                    pb.getFinalTime(), new double[pb.getDimension()]);


    assertEquals(integ.getEvaluations(), pb.getCalls());
    assertTrue(pb.getCalls() < 3300);


  }

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Examples of org.apache.commons.math.ode.TestProblem3

  }


  public void testVariableSteps()
    throws DerivativeException, IntegratorException {


    final TestProblem3 pb  = new TestProblem3(0.9);
    double minStep = 0;
    double maxStep = pb.getFinalTime() - pb.getInitialTime();
    double scalAbsoluteTolerance = 1.0e-8;
    double scalRelativeTolerance = scalAbsoluteTolerance;


    FirstOrderIntegrator integ = new DormandPrince853Integrator(minStep, maxStep,
                                                               scalAbsoluteTolerance,
                                                               scalRelativeTolerance);
    integ.addStepHandler(new VariableHandler());
    double stopTime = integ.integrate(pb,
                                      pb.getInitialTime(), pb.getInitialState(),
                                      pb.getFinalTime(), new double[pb.getDimension()]);
    assertEquals(pb.getFinalTime(), stopTime, 1.0e-10);
    assertEquals("Dormand-Prince 8 (5, 3)", integ.getName());
  }

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Examples of org.apache.commons.math.ode.TestProblem3

public class HighamHall54StepInterpolatorTest {


  @Test
  public void derivativesConsistency()
  throws DerivativeException, IntegratorException {
    TestProblem3 pb = new TestProblem3(0.1);
    double minStep = 0;
    double maxStep = pb.getFinalTime() - pb.getInitialTime();
    double scalAbsoluteTolerance = 1.0e-8;
    double scalRelativeTolerance = scalAbsoluteTolerance;
    HighamHall54Integrator integ = new HighamHall54Integrator(minStep, maxStep,
                                                              scalAbsoluteTolerance,
                                                              scalRelativeTolerance);

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Examples of org.apache.commons.math.ode.TestProblem3

  @Test
  public void serialization()
    throws DerivativeException, IntegratorException,
           IOException, ClassNotFoundException {


    TestProblem3 pb = new TestProblem3(0.9);
    double minStep = 0;
    double maxStep = pb.getFinalTime() - pb.getInitialTime();
    double scalAbsoluteTolerance = 1.0e-8;
    double scalRelativeTolerance = scalAbsoluteTolerance;
    HighamHall54Integrator integ = new HighamHall54Integrator(minStep, maxStep,
                                                              scalAbsoluteTolerance,
                                                              scalRelativeTolerance);
    integ.addStepHandler(new ContinuousOutputModel());
    integ.integrate(pb,
                    pb.getInitialTime(), pb.getInitialState(),
                    pb.getFinalTime(), new double[pb.getDimension()]);


    ByteArrayOutputStream bos = new ByteArrayOutputStream();
    ObjectOutputStream    oos = new ObjectOutputStream(bos);
    for (StepHandler handler : integ.getStepHandlers()) {
        oos.writeObject(handler);
    }


    assertTrue(bos.size () > 158000);
    assertTrue(bos.size () < 159000);


    ByteArrayInputStream  bis = new ByteArrayInputStream(bos.toByteArray());
    ObjectInputStream     ois = new ObjectInputStream(bis);
    ContinuousOutputModel cm  = (ContinuousOutputModel) ois.readObject();


    Random random = new Random(347588535632l);
    double maxError = 0.0;
    for (int i = 0; i < 1000; ++i) {
      double r = random.nextDouble();
      double time = r * pb.getInitialTime() + (1.0 - r) * pb.getFinalTime();
      cm.setInterpolatedTime(time);
      double[] interpolatedY = cm.getInterpolatedState ();
      double[] theoreticalY  = pb.computeTheoreticalState(time);
      double dx = interpolatedY[0] - theoreticalY[0];
      double dy = interpolatedY[1] - theoreticalY[1];
      double error = dx * dx + dy * dy;
      if (error > maxError) {
        maxError = error;

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