ptolemy.actor.lib
Class PoissonClock

java.lang.Object
  ptolemy.kernel.util.NamedObj
      ptolemy.kernel.InstantiableNamedObj
          ptolemy.kernel.Entity
              ptolemy.kernel.ComponentEntity
                  ptolemy.actor.AtomicActor
                      ptolemy.actor.TypedAtomicActor
                          ptolemy.actor.lib.Source
                              ptolemy.actor.lib.RandomSource
                                  ptolemy.actor.lib.PoissonClock

All Implemented Interfaces:

java.io.Serializable, java.lang.Cloneable, Actor, Executable, FiringsRecordable, Initializable, TimedActor, TypedActor, Changeable, Debuggable, DebugListener, Derivable, Instantiable, ModelErrorHandler, MoMLExportable, Moveable, Nameable

public class PoissonClock
extends RandomSource
implements TimedActor

This actor produces discrete events according to a Poisson process. The time between events is given by independent and identically distributed exponential random variables. The values produced rotate sequentially through those given in the values parameter, which is an array of anything and defaults to {1, 0}. The type of the output can be any token type. This type is inferred from the element type of the values parameter. The mean time between events is given by the meanTime parameter, which defaults to 1.0.

In the initialize() method and postfire() methods, the actor uses the fireAt() method of the director to request the next firing. The first firing is always at the start time, unless the parameter fireAtStart is changed to false.

If the trigger input is connected, then any event on it will cause the Poisson process to immediately produce the next event, as if the time for that event had arrived.

If this actor is inactive at the time at which it would have otherwise produced an output, then it will stop producing outputs. This should not happen.

Since:

Ptolemy II 1.0

Version:

$Id: PoissonClock.java 57046 2010-01-27 23:35:53Z cxh $

Author:

Edward A. Lee

See Also:

Serialized Form

Accepted Rating:

Yellow (yuhong)

Proposed Rating:

Yellow (eal)

Nested Class Summary

Nested classes/interfaces inherited from class ptolemy.kernel.Entity

Entity.ContainedObjectsIterator

Field Summary

private double	_current
private boolean	_executing
private int	_length
private Time	_nextFiringTime
private int	_nextOutputIndex
private Time	_stopTime
Parameter	fireAtStart If true, then this actor will request a firing at the start time.
Parameter	meanTime The mean time between events, where the output value transitions.
Parameter	stopTime The time at which postfire() should return false.
Parameter	values The values that will be produced at the output.

Fields inherited from class ptolemy.actor.lib.RandomSource

_generatorSeed, _needNew, _needNewGenerator, _random, resetOnEachRun, seed

Fields inherited from class ptolemy.actor.lib.Source

output, trigger

Fields inherited from class ptolemy.actor.AtomicActor

_actorFiringListeners, _initializables, _notifyingActorFiring, _stopRequested

Fields inherited from class ptolemy.kernel.util.NamedObj

_changeListeners, _changeLock, _changeRequests, _debugging, _debugListeners, _elementName, _isPersistent, _verbose, _workspace, ATTRIBUTES, CLASSNAME, COMPLETE, CONTENTS, DEEP, FULLNAME, LINKS

Fields inherited from interface ptolemy.actor.Executable

COMPLETED, NOT_READY, STOP_ITERATING

Constructor Summary

PoissonClock(CompositeEntity container, java.lang.String name)
Construct an actor with the specified container and name.

Method Summary

protected void	_generateRandomNumber() Generate a new random number.
private Token	_getValue(int index)
void	attributeChanged(Attribute attribute) If the argument is the meanTime parameter, check that it is positive.
java.lang.Object	clone(Workspace workspace) Clone the actor into the specified workspace.
void	fire() Output the current value.
Time	getModelStopTime() Get the stop time.
double	getStopTime() Deprecated. As of Ptolemy II 4.1, replaced by getModelStopTime()
void	initialize() Request the first firing either at the start time or at a random time, depending on fireAtStart.
boolean	postfire() Generate an exponential random number and schedule the next firing.
boolean	prefire() If the current time matches the expected time for the next output, then return true.
void	wrapup() Override the base class to reset a flag that indicates that the model is executing.

Methods inherited from class ptolemy.actor.lib.RandomSource

_createGenerator

Methods inherited from class ptolemy.actor.TypedAtomicActor

_addPort, _fireAt, _fireAt, attributeTypeChanged, clone, newPort, typeConstraintList, typeConstraints

Methods inherited from class ptolemy.actor.AtomicActor

_actorFiring, _actorFiring, addActorFiringListener, addInitializable, connectionsChanged, createReceivers, declareDelayDependency, getCausalityInterface, getDirector, getExecutiveDirector, getManager, inputPortList, isFireFunctional, isStrict, iterate, newReceiver, outputPortList, preinitialize, pruneDependencies, recordFiring, removeActorFiringListener, removeDependency, removeInitializable, setContainer, stop, stopFire, terminate

Methods inherited from class ptolemy.kernel.ComponentEntity

_adjustDeferrals, _checkContainer, _getContainedObject, _propagateExistence, getContainer, instantiate, isAtomic, isOpaque, moveDown, moveToFirst, moveToIndex, moveToLast, moveUp, propagateExistence, setName

Methods inherited from class ptolemy.kernel.Entity

_description, _exportMoMLContents, _removePort, _validateSettables, connectedPortList, connectedPorts, containedObjectsIterator, getAttribute, getPort, getPorts, linkedRelationList, linkedRelations, portList, removeAllPorts, setClassDefinition, uniqueName

Methods inherited from class ptolemy.kernel.InstantiableNamedObj

_setParent, exportMoML, getChildren, getElementName, getParent, getPrototypeList, isClassDefinition, isWithinClassDefinition

Methods inherited from class ptolemy.kernel.util.NamedObj

_addAttribute, _adjustOverride, _attachText, _cloneFixAttributeFields, _debug, _debug, _debug, _debug, _debug, _getIndentPrefix, _isMoMLSuppressed, _markContentsDerived, _propagateValue, _recordDecoratedAttributes, _removeAttribute, _splitName, _stripNumericSuffix, addChangeListener, addDebugListener, attributeList, attributeList, deepContains, depthInHierarchy, description, description, event, executeChangeRequests, exportMoML, exportMoML, exportMoML, exportMoML, exportMoMLPlain, getAttribute, getAttributes, getChangeListeners, getClassName, getDecoratorAttribute, getDecoratorAttributes, getDerivedLevel, getDerivedList, getDisplayName, getFullName, getModelErrorHandler, getName, getName, getSource, handleModelError, isDeferringChangeRequests, isOverridden, isPersistent, lazyContainedObjectsIterator, message, propagateValue, propagateValues, removeChangeListener, removeDebugListener, requestChange, setClassName, setDeferringChangeRequests, setDerivedLevel, setDisplayName, setModelErrorHandler, setPersistent, setSource, sortContainedObjects, toplevel, toString, validateSettables, workspace

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface ptolemy.actor.Actor

createReceivers, getCausalityInterface, getDirector, getExecutiveDirector, getManager, inputPortList, newReceiver, outputPortList

Methods inherited from interface ptolemy.actor.Executable

isFireFunctional, isStrict, iterate, stop, stopFire, terminate

Methods inherited from interface ptolemy.actor.Initializable

addInitializable, preinitialize, removeInitializable

Methods inherited from interface ptolemy.kernel.util.Nameable

description, getContainer, getDisplayName, getFullName, getName, getName, setName

Methods inherited from interface ptolemy.kernel.util.Derivable

getDerivedLevel, getDerivedList, propagateValue

Field Detail

fireAtStart

public Parameter fireAtStart

If true, then this actor will request a firing at the start time. Otherwise, the first firing will be requested at the first random time. This is a boolean-valued parameter that defaults to true.

meanTime

public Parameter meanTime

The mean time between events, where the output value transitions. This parameter must contain a DoubleToken.

stopTime

public Parameter stopTime

The time at which postfire() should return false. This is a double that defaults to Infinity, which means that postfire() never returns false (or at least, doesn't do so due to stopTime having been exceeded).

values

public Parameter values

The values that will be produced at the output. This parameter can contain any ArrayToken, and it defaults to {1, 0}.

_current

private double _current

_executing

private boolean _executing

_length

private transient int _length

_nextFiringTime

private transient Time _nextFiringTime

_nextOutputIndex

private transient int _nextOutputIndex

_stopTime

private Time _stopTime

Constructor Detail

PoissonClock

public PoissonClock(CompositeEntity container,
                    java.lang.String name)
             throws NameDuplicationException,
                    IllegalActionException

Construct an actor with the specified container and name.

Parameters:

container - The container.

name - The name of this actor.

Throws:

IllegalActionException - If the entity cannot be contained by the proposed container.

NameDuplicationException - If the container already has an actor with this name.

Method Detail

attributeChanged

public void attributeChanged(Attribute attribute)
                      throws IllegalActionException

If the argument is the meanTime parameter, check that it is positive.

Overrides:

attributeChanged in class RandomSource

Parameters:

attribute - The attribute that changed.

Throws:

IllegalActionException - If the meanTime value is not positive.

clone

public java.lang.Object clone(Workspace workspace)
                       throws java.lang.CloneNotSupportedException

Clone the actor into the specified workspace. This calls the base class and then sets the parameter public members to refer to the parameters of the new actor.

Overrides:

clone in class RandomSource

Parameters:

workspace - The workspace for the new object.

Returns:

A new actor.

Throws:

java.lang.CloneNotSupportedException - If a derived class contains an attribute that cannot be cloned.

See Also:

NamedObj.exportMoML(Writer, int, String), NamedObj.setDeferringChangeRequests(boolean)

fire

public void fire()
          throws IllegalActionException

Output the current value.

Specified by:

fire in interface Executable

Overrides:

fire in class RandomSource

Throws:

IllegalActionException - If there is no director.

getStopTime

public double getStopTime()

Deprecated. As of Ptolemy II 4.1, replaced by getModelStopTime()

Get the stop time.

Returns:

The stop time.

getModelStopTime

public Time getModelStopTime()

Get the stop time.

Returns:

The stop time.

initialize

public void initialize()
                throws IllegalActionException

Request the first firing either at the start time or at a random time, depending on fireAtStart.

Specified by:

initialize in interface Initializable

Overrides:

initialize in class RandomSource

Throws:

IllegalActionException - If the fireAt() method of the director throws it, or if the director does not agree to fire the actor at the specified time.

postfire

public boolean postfire()
                 throws IllegalActionException

Generate an exponential random number and schedule the next firing.

Specified by:

postfire in interface Executable

Overrides:

postfire in class RandomSource

Returns:

True if it is ok to continue.

Throws:

IllegalActionException - If the director throws it when scheduling the next firing, or if the director does not agree to fire the actor at the specified time.

prefire

public boolean prefire()
                throws IllegalActionException

If the current time matches the expected time for the next output, then return true. Also return true if the trigger input is connected and has events. Otherwise, return false.

Specified by:

prefire in interface Executable

Overrides:

prefire in class Source

Returns:

True, unless the trigger input is connected and has no input.

Throws:

IllegalActionException - If there is no director.

wrapup

public void wrapup()
            throws IllegalActionException

Override the base class to reset a flag that indicates that the model is executing. This method is invoked exactly once per execution of an application. None of the other action methods should be be invoked after it.

Specified by:

wrapup in interface Initializable

Overrides:

wrapup in class AtomicActor

Throws:

IllegalActionException - Not thrown in this base class.

_generateRandomNumber

protected void _generateRandomNumber()
                              throws IllegalActionException

Generate a new random number.

Specified by:

_generateRandomNumber in class RandomSource

Throws:

IllegalActionException - If parameter values are incorrect.

_getValue

private Token _getValue(int index)
                 throws IllegalActionException

Throws:

IllegalActionException