Package org.apache.commons.math.ode

Class AbstractIntegrator

java.lang.Object
org.apache.commons.math.ode.AbstractIntegrator
All Implemented Interfaces:
FirstOrderIntegrator, ODEIntegrator
Direct Known Subclasses:
AdaptiveStepsizeIntegrator, RungeKuttaIntegrator
public abstract class AbstractIntegrator extends Object implements FirstOrderIntegrator
Base class managing common boilerplate for all integrators.
Since:
2.0
Version:
$Revision: 1073267 $ $Date: 2011-02-22 10:06:20 +0100 (mar. 22 févr. 2011) $

  • Field Details

    • stepHandlers

      protected Collection<StepHandler> stepHandlers
      Step handler.

    • stepStart

      protected double stepStart
      Current step start time.

    • stepSize

      protected double stepSize
      Current stepsize.

    • isLastStep

      protected boolean isLastStep
      Indicator for last step.

    • resetOccurred

      protected boolean resetOccurred
      Indicator that a state or derivative reset was triggered by some event.

  • Constructor Details

    • AbstractIntegrator

      public AbstractIntegrator(String name)
      Build an instance.
      Parameters:
      name - name of the method

    • AbstractIntegrator

      protected AbstractIntegrator()
      Build an instance with a null name.

  • Method Details

    • getName

      public String getName()
      Get the name of the method.
      Specified by:
      getName in interface ODEIntegrator
      Returns:
      name of the method

    • addStepHandler

      public void addStepHandler(StepHandler handler)
      Add a step handler to this integrator.

      The handler will be called by the integrator for each accepted step.

      Specified by:
      addStepHandler in interface ODEIntegrator
      Parameters:
      handler - handler for the accepted steps
      See Also:

    • getStepHandlers

      public Collection<StepHandler> getStepHandlers()
      Get all the step handlers that have been added to the integrator.
      Specified by:
      getStepHandlers in interface ODEIntegrator
      Returns:
      an unmodifiable collection of the added events handlers
      See Also:

    • clearStepHandlers

      public void clearStepHandlers()
      Remove all the step handlers that have been added to the integrator.
      Specified by:
      clearStepHandlers in interface ODEIntegrator
      See Also:

    • addEventHandler

      public void addEventHandler(EventHandler handler, double maxCheckInterval, double convergence, int maxIterationCount)
      Add an event handler to the integrator.
      Specified by:
      addEventHandler in interface ODEIntegrator
      Parameters:
      handler - event handler
      maxCheckInterval - maximal time interval between switching function checks (this interval prevents missing sign changes in case the integration steps becomes very large)
      convergence - convergence threshold in the event time search
      maxIterationCount - upper limit of the iteration count in the event time search
      See Also:

    • getEventHandlers

      public Collection<EventHandler> getEventHandlers()
      Get all the event handlers that have been added to the integrator.
      Specified by:
      getEventHandlers in interface ODEIntegrator
      Returns:
      an unmodifiable collection of the added events handlers
      See Also:

    • clearEventHandlers

      public void clearEventHandlers()
      Remove all the event handlers that have been added to the integrator.
      Specified by:
      clearEventHandlers in interface ODEIntegrator
      See Also:

    • requiresDenseOutput

      protected boolean requiresDenseOutput()
      Check if dense output is needed.
      Returns:
      true if there is at least one event handler or if one of the step handlers requires dense output

    • getCurrentStepStart

      public double getCurrentStepStart()
      Get the current value of the step start time ti.

      This method can be called during integration (typically by the object implementing the differential equations problem) if the value of the current step that is attempted is needed.

      The result is undefined if the method is called outside of calls to integrate.

      Specified by:
      getCurrentStepStart in interface ODEIntegrator
      Returns:
      current value of the step start time ti

    • getCurrentSignedStepsize

      public double getCurrentSignedStepsize()
      Get the current signed value of the integration stepsize.

      This method can be called during integration (typically by the object implementing the differential equations problem) if the signed value of the current stepsize that is tried is needed.

      The result is undefined if the method is called outside of calls to integrate.

      Specified by:
      getCurrentSignedStepsize in interface ODEIntegrator
      Returns:
      current signed value of the stepsize

    • setMaxEvaluations

      public void setMaxEvaluations(int maxEvaluations)
      Set the maximal number of differential equations function evaluations.

      The purpose of this method is to avoid infinite loops which can occur for example when stringent error constraints are set or when lots of discrete events are triggered, thus leading to many rejected steps.

      Specified by:
      setMaxEvaluations in interface ODEIntegrator
      Parameters:
      maxEvaluations - maximal number of function evaluations (negative values are silently converted to maximal integer value, thus representing almost unlimited evaluations)

    • getMaxEvaluations

      public int getMaxEvaluations()
      Get the maximal number of functions evaluations.
      Specified by:
      getMaxEvaluations in interface ODEIntegrator
      Returns:
      maximal number of functions evaluations

    • getEvaluations

      public int getEvaluations()
      Get the number of evaluations of the differential equations function.

      The number of evaluations corresponds to the last call to the integrate method. It is 0 if the method has not been called yet.

      Specified by:
      getEvaluations in interface ODEIntegrator
      Returns:
      number of evaluations of the differential equations function

    • resetEvaluations

      protected void resetEvaluations()
      Reset the number of evaluations to zero.

    • setEquations

      protected void setEquations(FirstOrderDifferentialEquations equations)
      Set the differential equations.
      Parameters:
      equations - differential equations to integrate
      See Also:

    • computeDerivatives

      public void computeDerivatives(double t, double[] y, double[] yDot) throws DerivativeException
      Compute the derivatives and check the number of evaluations.
      Parameters:
      t - current value of the independent time variable
      y - array containing the current value of the state vector
      yDot - placeholder array where to put the time derivative of the state vector
      Throws:
      DerivativeException - this user-defined exception should be used if an error is is triggered by user code

    • setStateInitialized

      protected void setStateInitialized(boolean stateInitialized)
      Set the stateInitialized flag.

      This method must be called by integrators with the value false before they start integration, so a proper lazy initialization is done automatically on the first step.

      Parameters:
      stateInitialized - new value for the flag
      Since:
      2.2

    • acceptStep

      protected double acceptStep(AbstractStepInterpolator interpolator, double[] y, double[] yDot, double tEnd) throws DerivativeException, IntegratorException
      Accept a step, triggering events and step handlers.
      Parameters:
      interpolator - step interpolator
      y - state vector at step end time, must be reset if an event asks for resetting or if an events stops integration during the step
      yDot - placeholder array where to put the time derivative of the state vector
      tEnd - final integration time
      Returns:
      time at end of step
      Throws:
      DerivativeException - this exception is propagated to the caller if the underlying user function triggers one
      IntegratorException - if the value of one event state cannot be evaluated
      Since:
      2.2

    • sanityChecks

      protected void sanityChecks(FirstOrderDifferentialEquations ode, double t0, double[] y0, double t, double[] y) throws IntegratorException
      Perform some sanity checks on the integration parameters.
      Parameters:
      ode - differential equations set
      t0 - start time
      y0 - state vector at t0
      t - target time for the integration
      y - placeholder where to put the state vector
      Throws:
      IntegratorException - if some inconsistency is detected

    • addEndTimeChecker

      @Deprecated protected CombinedEventsManager addEndTimeChecker(double startTime, double endTime, CombinedEventsManager manager)
      Deprecated.
      as of 2.2, this method is not used any more
      Add an event handler for end time checking.

      This method can be used to simplify handling of integration end time. It leverages the nominal stop condition with the exceptional stop conditions.

      Parameters:
      startTime - integration start time
      endTime - desired end time
      manager - manager containing the user-defined handlers
      Returns:
      a new manager containing all the user-defined handlers plus a dedicated manager triggering a stop event at entTime