Package org.apache.commons.math.ode

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


    throws DerivativeException, IntegratorException {

    TestProblem1 pb = new TestProblem1();
    double step = (pb.getFinalTime() - pb.getInitialTime()) * 0.001;

    FirstOrderIntegrator integ = new GillIntegrator(step);
    TestProblemHandler handler = new TestProblemHandler(pb, integ);
    integ.addStepHandler(handler);
    integ.integrate(pb, pb.getInitialTime(), pb.getInitialState(),
                    pb.getFinalTime(), new double[pb.getDimension()]);

    assertTrue(handler.getLastError() < 2.0e-13);
    assertTrue(handler.getMaximalValueError() < 4.0e-12);
    assertEquals(0, handler.getMaximalTimeError(), 1.0e-12);
    assertEquals("Gill", integ.getName());

  }
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    throws DerivativeException, IntegratorException {

    TestProblem1 pb = new TestProblem1();
    double step = (pb.getFinalTime() - pb.getInitialTime()) * 0.2;

    FirstOrderIntegrator integ = new GillIntegrator(step);
    TestProblemHandler handler = new TestProblemHandler(pb, integ);
    integ.addStepHandler(handler);
    integ.integrate(pb, pb.getInitialTime(), pb.getInitialState(),
                    pb.getFinalTime(), new double[pb.getDimension()]);

    assertTrue(handler.getLastError() > 0.0004);
    assertTrue(handler.getMaximalValueError() > 0.005);
    assertEquals(0, handler.getMaximalTimeError(), 1.0e-12);
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      throws DerivativeException, IntegratorException {

      TestProblem5 pb = new TestProblem5();
      double step = Math.abs(pb.getFinalTime() - pb.getInitialTime()) * 0.001;

      FirstOrderIntegrator integ = new GillIntegrator(step);
      TestProblemHandler handler = new TestProblemHandler(pb, integ);
      integ.addStepHandler(handler);
      integ.integrate(pb, pb.getInitialTime(), pb.getInitialState(),
                      pb.getFinalTime(), new double[pb.getDimension()]);

      assertTrue(handler.getLastError() < 5.0e-10);
      assertTrue(handler.getMaximalValueError() < 7.0e-10);
      assertEquals(0, handler.getMaximalTimeError(), 1.0e-12);
      assertEquals("Gill", integ.getName());
  }
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    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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  }

  public void testUnstableDerivative()
  throws DerivativeException, IntegratorException {
    final StepProblem stepProblem = new StepProblem(0.0, 1.0, 2.0);
    FirstOrderIntegrator integ = new GillIntegrator(0.3);
    integ.addEventHandler(stepProblem, 1.0, 1.0e-12, 1000);
    double[] y = { Double.NaN };
    integ.integrate(stepProblem, 0.0, new double[] { 0.0 }, 10.0, y);
    assertEquals(8.0, y[0], 1.0e-12);
  }
View Full Code Here

  }

  public void testStepSize()
    throws DerivativeException, IntegratorException {
      final double step = 1.23456;
      FirstOrderIntegrator integ = new GillIntegrator(step);
      integ.addStepHandler(new StepHandler() {
          public void handleStep(StepInterpolator interpolator, boolean isLast) {
              if (! isLast) {
                  assertEquals(step,
                               interpolator.getCurrentTime() - interpolator.getPreviousTime(),
                               1.0e-12);
              }
          }
          public boolean requiresDenseOutput() {
              return false;
          }
          public void reset() {
          }
      });
      integ.integrate(new FirstOrderDifferentialEquations() {
          private static final long serialVersionUID = 0L;
          public void computeDerivatives(double t, double[] y, double[] dot) {
              dot[0] = 1.0;
          }
          public int getDimension() {
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      double minStep   = 0.1 * Math.abs(pb.getFinalTime() - pb.getInitialTime());
      double maxStep   = Math.abs(pb.getFinalTime() - pb.getInitialTime());
      double[] vecAbsoluteTolerance = { 1.0e-20, 1.0e-21 };
      double[] vecRelativeTolerance = { 1.0e-20, 1.0e-21 };

      FirstOrderIntegrator integ =
        new GraggBulirschStoerIntegrator(minStep, maxStep,
                                         vecAbsoluteTolerance, vecRelativeTolerance);
      TestProblemHandler handler = new TestProblemHandler(pb, integ);
      integ.addStepHandler(handler);
      integ.integrate(pb,
                      pb.getInitialTime(), pb.getInitialState(),
                      pb.getFinalTime(), new double[pb.getDimension()]);
      fail("an exception should have been thrown");
    } catch(DerivativeException de) {
      fail("wrong exception caught");
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      double minStep = 0;
      double maxStep = pb.getFinalTime() - pb.getInitialTime();
      double scalAbsoluteTolerance = 1.0e-8;
      double scalRelativeTolerance = 0.01 * scalAbsoluteTolerance;

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

      assertTrue(handler.getLastError() < 9.0e-10);
      assertTrue(handler.getMaximalValueError() < 9.0e-10);
      assertEquals(0, handler.getMaximalTimeError(), 1.0e-12);
      assertEquals("Gragg-Bulirsch-Stoer", integ.getName());
  }
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      double minStep      = 0;
      double maxStep      = pb.getFinalTime() - pb.getInitialTime();
      double absTolerance = Math.pow(10.0, i);
      double relTolerance = absTolerance;

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

      // the coefficients are only valid for this test
      // and have been obtained from trial and error
      // there is no general relation between local and global errors
      double ratio =  handler.getMaximalValueError() / absTolerance;
      assertTrue(ratio < 2.4);
      assertTrue(ratio > 0.02);
      assertEquals(0, handler.getMaximalTimeError(), 1.0e-12);

      int calls = pb.getCalls();
      assertEquals(integ.getEvaluations(), calls);
      assertTrue(calls <= previousCalls);
      previousCalls = calls;

    }
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    double minStep = 0;
    double maxStep = pb.getFinalTime() - pb.getInitialTime();
    double scalAbsoluteTolerance = 1.0e-10;
    double scalRelativeTolerance = 0.01 * scalAbsoluteTolerance;

    FirstOrderIntegrator integ = new GraggBulirschStoerIntegrator(minStep, maxStep,
                                                                  scalAbsoluteTolerance,
                                                                  scalRelativeTolerance);
    TestProblemHandler handler = new TestProblemHandler(pb, integ);
    integ.addStepHandler(handler);
    EventHandler[] functions = pb.getEventsHandlers();
    for (int l = 0; l < functions.length; ++l) {
      integ.addEventHandler(functions[l],
                                 Double.POSITIVE_INFINITY, 1.0e-8 * maxStep, 1000);
    }
    assertEquals(functions.length, integ.getEventHandlers().size());
    integ.integrate(pb,
                    pb.getInitialTime(), pb.getInitialState(),
                    pb.getFinalTime(), new double[pb.getDimension()]);

    assertTrue(handler.getMaximalValueError() < 5.0e-8);
    assertEquals(0, handler.getMaximalTimeError(), 1.0e-12);
    assertEquals(12.0, handler.getLastTime(), 1.0e-8 * maxStep);
    integ.clearEventHandlers();
    assertEquals(0, integ.getEventHandlers().size());

  }
View Full Code Here

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