org.apache.commons.math.ode.events
Class EventState

java.lang.Object
  extended by org.apache.commons.math.ode.events.EventState

public class EventState
extends java.lang.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 (and hence the step should be reduced to ensure the event occurs at a bound rather than inside the step).

Since:
1.2
Version:
$Revision: 1073158 $ $Date: 2011-02-21 22:46:52 +0100 (lun. 21 févr. 2011) $

Nested Class Summary
private static class EventState.EmbeddedDerivativeException
          Local exception for embedding DerivativeException.
private static class EventState.EmbeddedEventException
          Local exception for embedding EventException.
 
Field Summary
private  double convergence
          Convergence threshold for event localization.
private  boolean forward
          Integration direction.
private  double g0
          Value of the events handler at the beginning of the step.
private  boolean g0Positive
          Simulated sign of g0 (we cheat when crossing events).
private  EventHandler handler
          Event handler.
private  boolean increasing
          Variation direction around pending event.
private  double maxCheckInterval
          Maximal time interval between events handler checks.
private  int maxIterationCount
          Upper limit in the iteration count for event localization.
private  int nextAction
          Next action indicator.
private  boolean pendingEvent
          Indicator of event expected during the step.
private  double pendingEventTime
          Occurrence time of the pending event.
private  double previousEventTime
          Occurrence time of the previous event.
private  double t0
          Time at the beginning of the step.
 
Constructor Summary
EventState(EventHandler handler, double maxCheckInterval, double convergence, int maxIterationCount)
          Simple constructor.
 
Method Summary
 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 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
 

Field Detail

handler

private final EventHandler handler
Event handler.


maxCheckInterval

private final double maxCheckInterval
Maximal time interval between events handler checks.


convergence

private final double convergence
Convergence threshold for event localization.


maxIterationCount

private final int maxIterationCount
Upper limit in the iteration count for event localization.


t0

private double t0
Time at the beginning of the step.


g0

private double g0
Value of the events handler at the beginning of the step.


g0Positive

private boolean g0Positive
Simulated sign of g0 (we cheat when crossing events).


pendingEvent

private boolean pendingEvent
Indicator of event expected during the step.


pendingEventTime

private double pendingEventTime
Occurrence time of the pending event.


previousEventTime

private double previousEventTime
Occurrence time of the previous event.


forward

private boolean forward
Integration direction.


increasing

private boolean increasing
Variation direction around pending event. (this is considered with respect to the integration direction)


nextAction

private int nextAction
Next action indicator.

Constructor Detail

EventState

public EventState(EventHandler handler,
                  double maxCheckInterval,
                  double convergence,
                  int maxIterationCount)
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
Method Detail

getEventHandler

public EventHandler getEventHandler()
Get the underlying event handler.

Returns:
underlying event handler

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 EventException
Reinitialize the beginning of the step.

Parameters:
interpolator - valid for the current step
Throws:
EventException - if the event handler value cannot be evaluated at the beginning of the step

evaluateStep

public boolean evaluateStep(StepInterpolator interpolator)
                     throws DerivativeException,
                            EventException,
                            ConvergenceException
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:
EventState.EmbeddedDerivativeException - if the interpolator fails to compute the switching function somewhere within the step
EventException - if the switching function cannot be evaluated
ConvergenceException - if an event cannot be located
DerivativeException

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 positive infinity if no events are triggered

stepAccepted

public void stepAccepted(double t,
                         double[] y)
                  throws EventException
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
Throws:
EventException - if the value of the event handler cannot be evaluated

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)
              throws EventException
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
Throws:
EventException - if the state cannot be reseted by the event handler


Copyright (c) 2003-2011 Apache Software Foundation