Package org.apache.commons.math.ode

Class AbstractIntegrator

    • Field Detail

      • stepHandlers

        protected java.util.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 Detail

      • AbstractIntegrator

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

      • AbstractIntegrator

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

    • Method Detail

      • getName

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

      • 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:
        ODEIntegrator.getEventHandlers(), ODEIntegrator.clearEventHandlers()

      • 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.

      • 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