org.apache.commons.math3.ode.events

## Class EventState

- java.lang.Object
- - org.apache.commons.math3.ode.events.EventState

-     public class EventState
      extends Object

  This class handles the state for one `event handler` during integration steps.

  Each time the integrator proposes a step, the event handler switching function should be checked. This class handles the state of one handler during one integration step, with references to the state at the end of the preceding step. This information is used to decide if the handler should trigger an event or not during the proposed step.

  Since:
    1.2

- - ### Constructor Summary

    Constructors
    Constructor and Description
    `EventState(EventHandler handler, double maxCheckInterval, double convergence, int maxIterationCount, UnivariateSolver solver)` Simple constructor.

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `boolean` | `evaluateStep(StepInterpolator interpolator)` Evaluate the impact of the proposed step on the event handler.
    `double` | `getConvergence()` Get the convergence threshold for event localization.
    `EventHandler` | `getEventHandler()` Get the underlying event handler.
    `double` | `getEventTime()` Get the occurrence time of the event triggered in the current step.
    `double` | `getMaxCheckInterval()` Get the maximal time interval between events handler checks.
    `int` | `getMaxIterationCount()` Get the upper limit in the iteration count for event localization.
    `void` | `reinitializeBegin(StepInterpolator interpolator)` Reinitialize the beginning of the step.
    `boolean` | `reset(double t, double[] y)` Let the event handler reset the state if it wants.
    `void` | `setExpandable(ExpandableStatefulODE expandable)` Set the equation.
    `void` | `stepAccepted(double t, double[] y)` Acknowledge the fact the step has been accepted by the integrator.
    `boolean` | `stop()` Check if the integration should be stopped at the end of the current step.

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- - ### Constructor Detail

    - #### EventState

          public EventState(EventHandler handler,
                    double maxCheckInterval,
                    double convergence,
                    int maxIterationCount,
                    UnivariateSolver solver)

      Simple constructor.
      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` - Root-finding algorithm to use to detect state events

  - ### Method Detail

    - #### getEventHandler

          public EventHandler getEventHandler()

      Get the underlying event handler.
      Returns:
        underlying event handler

    - #### setExpandable

          public void setExpandable(ExpandableStatefulODE expandable)

      Set the equation.
      Parameters:
        `expandable` - equation being integrated

    - #### getMaxCheckInterval

          public double getMaxCheckInterval()

      Get the maximal time interval between events handler checks.
      Returns:
        maximal time interval between events handler checks

    - #### getConvergence

          public double getConvergence()

      Get the convergence threshold for event localization.
      Returns:
        convergence threshold for event localization

    - #### getMaxIterationCount

          public int getMaxIterationCount()

      Get the upper limit in the iteration count for event localization.
      Returns:
        upper limit in the iteration count for event localization

    - #### reinitializeBegin

          public void reinitializeBegin(StepInterpolator interpolator)
                                 throws MaxCountExceededException

      Reinitialize the beginning of the step.
      Parameters:
        `interpolator` - valid for the current step
      Throws:
        `MaxCountExceededException` - if the interpolator throws one because the number of functions evaluations is exceeded

    - #### evaluateStep

          public boolean evaluateStep(StepInterpolator interpolator)
                               throws MaxCountExceededException,
                                      NoBracketingException

      Evaluate the impact of the proposed step on the event handler.
      Parameters:
        `interpolator` - step interpolator for the proposed step
      Returns:
        true if the event handler triggers an event before the end of the proposed step
      Throws:
        `MaxCountExceededException` - if the interpolator throws one because the number of functions evaluations is exceeded
        `NoBracketingException` - if the event cannot be bracketed

    - #### getEventTime

          public double getEventTime()

      Get the occurrence time of the event triggered in the current step.
      Returns:
        occurrence time of the event triggered in the current step or infinity if no events are triggered

    - #### stepAccepted

          public void stepAccepted(double t,
                          double[] y)

      Acknowledge the fact the step has been accepted by the integrator.
      Parameters:
        `t` - value of the independent time variable at the end of the step
        `y` - array containing the current value of the state vector at the end of the step

    - #### stop

          public boolean stop()

      Check if the integration should be stopped at the end of the current step.
      Returns:
        true if the integration should be stopped

    - #### reset

          public boolean reset(double t,
                      double[] y)

      Let the event handler reset the state if it wants.
      Parameters:
        `t` - value of the independent time variable at the beginning of the next step
        `y` - array were to put the desired state vector at the beginning of the next step
      Returns:
        true if the integrator should reset the derivatives too

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