ptolemy.actor.lib
Class Lattice

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.Transformer
                              ptolemy.actor.lib.Lattice

All Implemented Interfaces:

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

Direct Known Subclasses:

GradientAdaptiveLattice, GradientAdaptiveLattice, VariableLattice

public class Lattice
extends Transformer

An FIR filter with a lattice structure. The coefficients of such a filter are called "reflection coefficients." Lattice filters are typically used as linear predictors because it is easy to ensure that they are minimum phase, and hence that their inverse is stable. A lattice filter is (strictly) minimum phase if its reflection coefficients are all less than unity in magnitude. To get the reflection coefficients for a linear predictor for a particular random process, you can use the LevinsonDurbin actor. The inputs and outputs are of type double.

The default reflection coefficients correspond to the optimal linear predictor for an AR process generated by filtering white noise with the following filter:

                            1
 H(z) =  --------------------------------------
         1 - 2z-1 + 1.91z-2 - 0.91z-3 + 0.205z-4
 

Since this filter is minimum phase, the transfer function of the lattice filter is H ^-1(z).

Note that the definition of reflection coefficients is not quite universal in the literature. The reflection coefficients in reference [2] are the negative of the ones used by this actor, which correspond to the definition in most other texts, and to the definition of partial-correlation (PARCOR) coefficients in the statistics literature.

The signs of the coefficients used in this actor are appropriate for values given by the LevinsonDurbin actor. The structure of the filter is as follows:

      y[0]              y[1]               y[n-1]           y[n]
 X(n) -------o-->-(+)-->----o-->-(+)-->-- ... ->---o-->-(+)------>  Y(n)
      |       \   /          \   /                  \   /
      |      +K1 /          +K2 /                  +Kn /
      |         X              X                      X
      V      -K1 \          -K2 \                  -Kn \
      |       /   \          /   \                  /   \
      \-[z]--o-->-(+)-[z]---o-->-(+)-[z]- ... ->---o-->-(+)
           w[0]         w[1]               w[n-1]           w[n]
 

References

[1] J. Makhoul, "Linear Prediction: A Tutorial Review", Proc. IEEE, Vol. 63, pp. 561-580, Apr. 1975.

[2] S. M. Kay, Modern Spectral Estimation: Theory & Application, Prentice-Hall, Englewood Cliffs, NJ, 1988.

Since:

Ptolemy II 1.0

Version:

$Id: Lattice.java 57040 2010-01-27 20:52:32Z cxh $

Author:

Edward A. Lee, Christopher Hylands, Steve Neuendorffer

See Also:

FIR, LevinsonDurbin, RecursiveLattice, VariableLattice, Serialized Form

Accepted Rating:

Yellow (cxh)

Proposed Rating:

Yellow (eal)

Nested Class Summary

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

Entity.ContainedObjectsIterator

Field Summary

protected double[]	_backward Backward prediction errors.
protected double[]	_backwardCache Cache of backward prediction errors.
protected double[]	_forward Forward prediction errors.
protected double[]	_forwardCache Cache of forward prediction errors.
protected int	_order The order of the filter (i.e. the number of reflection coefficients)
protected double[]	_reflectionCoefficients Cache of reflection coefficients.
Parameter	reflectionCoefficients The reflection coefficients.

Fields inherited from class ptolemy.actor.lib.Transformer

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

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

Method Summary

protected void	_doFilter() Compute the filter, updating the caches, based on the current values.
protected void	_reallocate() Reallocate the internal arrays.
void	attributeChanged(Attribute attribute) If the argument is the reflectionCoefficients parameter, then reallocate the arrays to use.
java.lang.Object	clone(Workspace workspace) Clone the actor into the specified workspace.
void	fire() Consume one input token, if there is one, and produce one output token.
void	initialize() Initialize the state of the filter.
boolean	postfire() Update the backward and forward prediction errors that were generated in fire() method.
boolean	prefire() Check to see if this actor is ready to fire.

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, 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, 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, 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

reflectionCoefficients

public Parameter reflectionCoefficients

The reflection coefficients. This is an array of doubles with default value {0.804534, -0.820577, 0.521934, -0.205}. These are the reflection coefficients for the linear predictor of a particular random process.

_order

protected int _order

The order of the filter (i.e. the number of reflection coefficients)

_backward

protected double[] _backward

Backward prediction errors. The length is _order.

_backwardCache

protected double[] _backwardCache

Cache of backward prediction errors. The fire() method updates _forwardCache and postfire() copies _forwardCache to _forward so this actor will work in domains like SR. The length is _order.

_forward

protected double[] _forward

Forward prediction errors. The length is _order + 1.

_forwardCache

protected double[] _forwardCache

Cache of forward prediction errors. The fire() method updates _forwardCache and postfire() copies _forwardCache to _forward so this actor will work in domains like SR. The length is _order + 1.

_reflectionCoefficients

protected double[] _reflectionCoefficients

Cache of reflection coefficients. The length is _order.

Constructor Detail

Lattice

public Lattice(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

attributeChanged

public void attributeChanged(Attribute attribute)
                      throws IllegalActionException

If the argument is the reflectionCoefficients parameter, then reallocate the arrays to use.

Overrides:

attributeChanged in class NamedObj

Parameters:

attribute - The attribute that changed.

Throws:

IllegalActionException - If the base class throws it.

clone

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

Clone the actor into the specified workspace.

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 contains an attribute that cannot be cloned.

See Also:

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

fire

public void fire()
          throws IllegalActionException

Consume one input token, if there is one, and produce one output token. If there is no input, the produce no output.

Specified by:

fire in interface Executable

Overrides:

fire in class AtomicActor

Throws:

IllegalActionException - If there is no director.

initialize

public void initialize()
                throws IllegalActionException

Initialize the state of the filter.

Specified by:

initialize in interface Initializable

Overrides:

initialize in class AtomicActor

Throws:

IllegalActionException - If a derived class throws it.

postfire

public boolean postfire()
                 throws IllegalActionException

Update the backward and forward prediction errors that were generated in fire() method.

Specified by:

postfire in interface Executable

Overrides:

postfire in class AtomicActor

Returns:

False if the number of iterations matches the number requested.

Throws:

IllegalActionException - If there is no director.

prefire

public boolean prefire()
                throws IllegalActionException

Check to see if this actor is ready to fire.

Specified by:

prefire in interface Executable

Overrides:

prefire in class AtomicActor

Returns:

True if this actor is ready for firing, false otherwise.

Throws:

IllegalActionException - If there is no director.

_doFilter

protected void _doFilter()
                  throws IllegalActionException

Compute the filter, updating the caches, based on the current values.

Throws:

IllegalActionException - Not thrown in this base class.

_reallocate

protected void _reallocate()

Reallocate the internal arrays.