Examples of org.apache.commons.math3.ode.FirstOrderIntegrator.integrate()

Class org.apache.commons.math3.ode.FirstOrderIntegrator

Examples of org.apache.commons.math3.ode.FirstOrderIntegrator.integrate()

org.apache.commons.math3.ode.FirstOrderIntegrator.integrate()
Integrate the differential equations up to the given time.
This method solves an Initial Value Problem (IVP).

Since this method stores some internal state variables made available in its public interface during integration ( {@link #getCurrentSignedStepsize()}), it is not thread-safe.
@param equations differential equations to integrate @param t0 initial time @param y0 initial value of the state vector at t0 @param t target time for the integration(can be set to a value smaller than t0 for backward integration) @param y placeholder where to put the state vector at each successfulstep (and hence at the end of integration), can be the same object as y0 @return stop time, will be the same as target time if integration reached itstarget, but may be different if some {@link org.apache.commons.math3.ode.events.EventHandler} stops it at some point. @exception DimensionMismatchException if arrays dimension do not match equations settings @exception NumberIsTooSmallException if integration step is too small @exception MaxCountExceededException if the number of functions evaluations is exceeded @exception NoBracketingException if the location of an event cannot be bracketed

                                   new BracketingNthOrderBrentSolver(1.0e-7, 5));
        double t0 = 0.5 * FastMath.PI;
        double tEnd = 5.5 * FastMath.PI;
        double[] y = { 0.0, 1.0 };
        Assert.assertEquals(tEnd,
                            integrator.integrate(new SineCosine(), t0, y, tEnd, y),
                            1.0e-7);


        Assert.assertEquals(5, allEvents.getEventCount());
        Assert.assertEquals(3, onlyDecreasing.getEventCount());

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                                   new BracketingNthOrderBrentSolver(1.0e-7, 5));
        double t0 = 0.5 * FastMath.PI;
        double tEnd = 5.5 * FastMath.PI;
        double[] y = { 0.0, 1.0 };
        Assert.assertEquals(tEnd,
                            integrator.integrate(new SineCosine(), t0, y, tEnd, y),
                            1.0e-7);


        Assert.assertEquals(5, allEvents.getEventCount());
        Assert.assertEquals(2, onlyIncreasing.getEventCount());
        Assert.assertEquals(3, onlyDecreasing.getEventCount());

View Full Code Here

      FirstOrderIntegrator integ = new DormandPrince853Integrator(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()]);
      Assert.fail("an exception should have been thrown");


  }

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      FirstOrderIntegrator integ = new DormandPrince853Integrator(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()]);


      Assert.assertTrue(handler.getLastError() < 1.1e-7);
      Assert.assertTrue(handler.getMaximalValueError() < 1.1e-7);
      Assert.assertEquals(0, handler.getMaximalTimeError(), 1.0e-12);

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        integ.addStepHandler(new StepNormalizer(0.5, this, mode, bounds));
        double[] y   = {0.0};
        double start = reverse ? getEnd()   : getStart();
        double end   = reverse ? getStart() : getEnd();
        output       = new ArrayList<Double>();
        integ.integrate(this, start, y, end, y);
        double[] actual = new double[output.size()];
        for(int i = 0; i < actual.length; i++) {
            actual[i] = output.get(i);
        }
        assertArrayEquals(expected, actual, 1e-5);

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        EventHandler[] functions = pb.getEventsHandlers();
        for (int l = 0; l < functions.length; ++l) {
          integ.addEventHandler(functions[l],
                                     Double.POSITIVE_INFINITY, 1.0e-6 * step, 1000);
        }
        double stopTime = integ.integrate(pb, pb.getInitialTime(), pb.getInitialState(),
                                          pb.getFinalTime(), new double[pb.getDimension()]);
        if (functions.length == 0) {
            Assert.assertEquals(pb.getFinalTime(), stopTime, 1.0e-10);
        }

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


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


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

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


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


    Assert.assertTrue(handler.getLastError() > 0.0004);
    Assert.assertTrue(handler.getMaximalValueError() > 0.005);
    Assert.assertEquals(0, handler.getMaximalTimeError(), 1.0e-12);

View Full Code Here

      double step = FastMath.abs(pb.getFinalTime() - pb.getInitialTime()) * 0.001;


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


      Assert.assertTrue(handler.getLastError() < 5.0e-10);
      Assert.assertTrue(handler.getMaximalValueError() < 7.0e-10);
      Assert.assertEquals(0, handler.getMaximalTimeError(), 1.0e-12);

View Full Code Here

    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()]);
  }


  private static class KeplerHandler implements StepHandler {

View Full Code Here

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