Package org.apache.commons.math3.ode

Class AbstractIntegrator

java.lang.Object
org.apache.commons.math3.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

  • 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. Uses a default UnivariateSolver with an absolute accuracy equal to the given convergence threshold, as root-finding algorithm to detect the state events.
      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:

    • addEventHandler

      public void addEventHandler(EventHandler handler, double maxCheckInterval, double convergence, int maxIterationCount, UnivariateSolver solver)
      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
      solver - The root-finding algorithm to use to detect the state events.
      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:

    • 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

    • initIntegration

      protected void initIntegration(double t0, double[] y0, double t)
      Prepare the start of an integration.
      Parameters:
      t0 - start value of the independent time variable
      y0 - array containing the start value of the state vector
      t - target time for the integration

    • setEquations

      protected void setEquations(ExpandableStatefulODE equations)
      Set the equations.
      Parameters:
      equations - equations to set

    • getExpandable

      protected ExpandableStatefulODE getExpandable()
      Get the differential equations to integrate.
      Returns:
      differential equations to integrate
      Since:
      3.2

    • getEvaluationsCounter

      @Deprecated protected Incrementor getEvaluationsCounter()
      Deprecated.
      as of 3.6 replaced with getCounter()
      Get the evaluations counter.
      Returns:
      evaluations counter
      Since:
      3.2

    • getCounter

      protected IntegerSequence.Incrementor getCounter()
      Get the evaluations counter.
      Returns:
      evaluations counter
      Since:
      3.6

    • integrate

      public double integrate(FirstOrderDifferentialEquations equations, double t0, double[] y0, double t, double[] y) throws DimensionMismatchException, NumberIsTooSmallException, MaxCountExceededException, NoBracketingException
      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 (ODEIntegrator.getCurrentSignedStepsize()), it is not thread-safe.

      Specified by:
      integrate in interface FirstOrderIntegrator
      Parameters:
      equations - differential equations to integrate
      t0 - initial time
      y0 - initial value of the state vector at t0
      t - target time for the integration (can be set to a value smaller than t0 for backward integration)
      y - placeholder where to put the state vector at each successful step (and hence at the end of integration), can be the same object as y0
      Returns:
      stop time, will be the same as target time if integration reached its target, but may be different if some EventHandler stops it at some point.
      Throws:
      DimensionMismatchException - if arrays dimension do not match equations settings
      NumberIsTooSmallException - if integration step is too small
      MaxCountExceededException - if the number of functions evaluations is exceeded
      NoBracketingException - if the location of an event cannot be bracketed

    • integrate

      public abstract void integrate(ExpandableStatefulODE equations, double t) throws NumberIsTooSmallException, DimensionMismatchException, MaxCountExceededException, NoBracketingException
      Integrate a set of differential equations up to the given time.

      This method solves an Initial Value Problem (IVP).

      The set of differential equations is composed of a main set, which can be extended by some sets of secondary equations. The set of equations must be already set up with initial time and partial states. At integration completion, the final time and partial states will be available in the same object.

      Since this method stores some internal state variables made available in its public interface during integration (getCurrentSignedStepsize()), it is not thread-safe.

      Parameters:
      equations - complete set of differential equations to integrate
      t - target time for the integration (can be set to a value smaller than t0 for backward integration)
      Throws:
      NumberIsTooSmallException - if integration step is too small
      DimensionMismatchException - if the dimension of the complete state does not match the complete equations sets dimension
      MaxCountExceededException - if the number of functions evaluations is exceeded
      NoBracketingException - if the location of an event cannot be bracketed

    • computeDerivatives

      public void computeDerivatives(double t, double[] y, double[] yDot) throws MaxCountExceededException, DimensionMismatchException, NullPointerException
      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:
      MaxCountExceededException - if the number of functions evaluations is exceeded
      DimensionMismatchException - if arrays dimensions do not match equations settings
      NullPointerException - if the ODE equations have not been set (i.e. if this method is called outside of a call to integrate(ExpandableStatefulODE, double) or integrate(FirstOrderDifferentialEquations, double, double[], double, double[]))

    • 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 MaxCountExceededException, DimensionMismatchException, NoBracketingException
      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:
      MaxCountExceededException - if the interpolator throws one because the number of functions evaluations is exceeded
      NoBracketingException - if the location of an event cannot be bracketed
      DimensionMismatchException - if arrays dimensions do not match equations settings
      Since:
      2.2

    • sanityChecks

      protected void sanityChecks(ExpandableStatefulODE equations, double t) throws NumberIsTooSmallException, DimensionMismatchException
      Check the integration span.
      Parameters:
      equations - set of differential equations
      t - target time for the integration
      Throws:
      NumberIsTooSmallException - if integration span is too small
      DimensionMismatchException - if adaptive step size integrators tolerance arrays dimensions are not compatible with equations settings