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

  }


  @Test
  public void checkClone()
  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;
    HighamHall54Integrator integ = new HighamHall54Integrator(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

  }


  public void testKepler()
    throws DerivativeException, IntegratorException {


    final TestProblem3 pb  = new TestProblem3(0.9);
    double step = (pb.getFinalTime() - pb.getInitialTime()) * 0.0003;


    FirstOrderIntegrator integ = new ThreeEighthesIntegrator(step);
    integ.addStepHandler(new KeplerHandler(pb));
    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

  }


  public void testKepler()
    throws DerivativeException, IntegratorException {


    final TestProblem3 pb  = new TestProblem3(0.9);
    double step = (pb.getFinalTime() - pb.getInitialTime()) * 0.0003;


    FirstOrderIntegrator integ = new GillIntegrator(step);
    integ.addStepHandler(new KeplerStepHandler(pb));
    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

  }


  public void testIntegratorControls()
  throws DerivativeException, IntegratorException {


    TestProblem3 pb = new TestProblem3(0.999);
    GraggBulirschStoerIntegrator integ =
        new GraggBulirschStoerIntegrator(0, pb.getFinalTime() - pb.getInitialTime(),
                1.0e-8, 1.0e-10);


    double errorWithDefaultSettings = getMaxError(integ, pb);


    // stability control

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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 absTolerance   = 1.0e-6;
    double relTolerance   = 1.0e-6;


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


    assertEquals(integ.getEvaluations(), pb.getCalls());
    assertTrue(pb.getCalls() < 2150);


  }

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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 absTolerance   = 1.0e-8;
    double relTolerance   = 1.0e-8;
    FirstOrderIntegrator integ =
      new GraggBulirschStoerIntegrator(minStep, maxStep,
                                       absTolerance, relTolerance);
    integ.addStepHandler(new VariableStepHandler());
    double stopTime = integ.integrate(pb,
                                      pb.getInitialTime(), pb.getInitialState(),
                                      pb.getFinalTime(), new double[pb.getDimension()]);
    assertEquals(pb.getFinalTime(), stopTime, 1.0e-10);
    assertEquals("Gragg-Bulirsch-Stoer", integ.getName());
  }

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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 step = (pb.getFinalTime() - pb.getInitialTime()) * 0.0003;


    FirstOrderIntegrator integ = new ClassicalRungeKuttaIntegrator(step);
    integ.addStepHandler(new KeplerHandler(pb));
    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


}


  public void testSanityChecks() {
    try {
      final TestProblem3 pb  = new TestProblem3(0.9);
      double minStep = 0;
      double maxStep = pb.getFinalTime() - pb.getInitialTime();


      try {
        FirstOrderIntegrator integ =
            new HighamHall54Integrator(minStep, maxStep, new double[4], new double[4]);
        integ.integrate(pb, pb.getInitialTime(), new double[6],
                        pb.getFinalTime(), new double[pb.getDimension()]);
        fail("an exception should have been thrown");
      } catch (IntegratorException ie) {
        // expected behavior
      }


      try {
        FirstOrderIntegrator integ =
            new HighamHall54Integrator(minStep, maxStep, new double[4], new double[4]);
        integ.integrate(pb, pb.getInitialTime(), pb.getInitialState(),
                        pb.getFinalTime(), new double[6]);
        fail("an exception should have been thrown");
      } catch (IntegratorException ie) {
        // expected behavior
      }


      try {
        FirstOrderIntegrator integ =
            new HighamHall54Integrator(minStep, maxStep, new double[2], new double[4]);
        integ.integrate(pb, pb.getInitialTime(), pb.getInitialState(),
                        pb.getFinalTime(), new double[pb.getDimension()]);
        fail("an exception should have been thrown");
      } catch (IntegratorException ie) {
        // expected behavior
      }


      try {
        FirstOrderIntegrator integ =
            new HighamHall54Integrator(minStep, maxStep, new double[4], new double[2]);
        integ.integrate(pb, pb.getInitialTime(), pb.getInitialState(),
                        pb.getFinalTime(), new double[pb.getDimension()]);
        fail("an exception should have been thrown");
      } catch (IntegratorException ie) {
        // expected behavior
      }


      try {
        FirstOrderIntegrator integ =
            new HighamHall54Integrator(minStep, maxStep, new double[4], new double[4]);
        integ.integrate(pb, pb.getInitialTime(), pb.getInitialState(),
                        pb.getInitialTime(), new double[pb.getDimension()]);
        fail("an exception should have been thrown");
      } catch (IntegratorException ie) {
        // expected behavior
      }

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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[] vecAbsoluteTolerance = { 1.0e-8, 1.0e-8, 1.0e-10, 1.0e-10 };
    double[] vecRelativeTolerance = { 1.0e-10, 1.0e-10, 1.0e-8, 1.0e-8 };


    FirstOrderIntegrator integ = new HighamHall54Integrator(minStep, maxStep,
                                                            vecAbsoluteTolerance,
                                                            vecRelativeTolerance);
    integ.addStepHandler(new KeplerHandler(pb));
    integ.integrate(pb,
                    pb.getInitialTime(), pb.getInitialState(),
                    pb.getFinalTime(), new double[pb.getDimension()]);
    assertEquals("Higham-Hall 5(4)", integ.getName());
  }

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

  }


  @Test
  public void derivativesConsistency()
  throws DerivativeException, IntegratorException {
    TestProblem3 pb = new TestProblem3();
    double step = (pb.getFinalTime() - pb.getInitialTime()) * 0.001;
    EulerIntegrator integ = new EulerIntegrator(step);
    StepInterpolatorTestUtils.checkDerivativesConsistency(integ, pb, 1.0e-10);
  }

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