ptolemy.domains.de.lib
Class Derivative

java.lang.Object
  ptolemy.kernel.util.NamedObj
      ptolemy.kernel.InstantiableNamedObj
          ptolemy.kernel.Entity
              ptolemy.kernel.ComponentEntity
                  ptolemy.actor.AtomicActor
                      ptolemy.actor.TypedAtomicActor
                          ptolemy.domains.de.kernel.DEActor
                              ptolemy.domains.de.lib.DETransformer
                                  ptolemy.domains.de.lib.Derivative

All Implemented Interfaces:

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

public class Derivative
extends DETransformer

Output the discrete derivative of the input, y[n] = (x[n] - x[n-1])/dt, where dt is the time gap between input events. Output is not generated until two inputs have been consumed.

The output of this actor is constrained to be a double, and input must be castable to a double. If the input signal is not left-continuous, the derivative will be either infinite or undefined and an exception is thrown.

In postfire(), if an event is present on the reset port, this actor resets to its initial state, and will not output until two subsequent inputs have been consumed. This is useful if the input signal is switched on and off, in which case the time gap between events becomes large and would otherwise effect the value of the derivative for one sample.

Since:

Ptolemy II 8.0

Version:

$Id: Derivative.java$

Author:

Jeff C. Jensen

See Also:

Differential, Serialized Form

Nested Class Summary

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

Entity.ContainedObjectsIterator

Field Summary

private TimedEvent	_currentInput
private TimedEvent	_lastInput
TypedIOPort	reset The reset port, which has undeclared type.

Fields inherited from class ptolemy.domains.de.lib.DETransformer

input, output

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

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

Method Summary

java.lang.Object	clone(Workspace workspace) Clone the actor into the specified workspace.
void	fire() Consume at most one token from the input port and output its value minus the value of the input read in the previous iteration, divided by the time gap between the two events.
void	initialize() Reset to indicate that no input has yet been seen.
boolean	postfire() Record the most recent input as the latest input.

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, prefire, preinitialize, pruneDependencies, recordFiring, removeActorFiringListener, removeDependency, removeInitializable, setContainer, stop, stopFire, terminate, wrapup

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, attributeChanged, 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, prefire, stop, stopFire, terminate

Methods inherited from interface ptolemy.actor.Initializable

addInitializable, preinitialize, removeInitializable, wrapup

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

reset

public TypedIOPort reset

The reset port, which has undeclared type. If this port receives a token, this actor resets to its initial state, and no output is generated until two inputs have been received.

_currentInput

private TimedEvent _currentInput

_lastInput

private TimedEvent _lastInput

Constructor Detail

Derivative

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

Construct an actor with the given container and name.

Parameters:

container - The container.

name - The name of this actor.

Throws:

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

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

Method Detail

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 ports.

Overrides:

clone in class AtomicActor

Parameters:

workspace - The workspace for the new object.

Returns:

A new actor.

Throws:

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

See Also:

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

fire

public void fire()
          throws IllegalActionException

Consume at most one token from the input port and output its value minus the value of the input read in the previous iteration, divided by the time gap between the two events. If there has been no previous iteration, no output is sent. If there is no input, then produce no output.

Specified by:

fire in interface Executable

Overrides:

fire in class AtomicActor

Throws:

IllegalActionException - If subtraction or division is not supported by the supplied tokens.

initialize

public void initialize()
                throws IllegalActionException

Reset to indicate that no input has yet been seen.

Specified by:

initialize in interface Initializable

Overrides:

initialize in class AtomicActor

Throws:

IllegalActionException - If the parent class throws it.

postfire

public boolean postfire()
                 throws IllegalActionException

Record the most recent input as the latest input. If a reset event has been received, process it here.

Specified by:

postfire in interface Executable

Overrides:

postfire in class AtomicActor

Returns:

True if execution can continue into the next iteration.

Throws:

IllegalActionException - If the base class throws it.