ptolemy.domains.ct.kernel.solver
Class ExplicitRK23Solver

java.lang.Object
  ptolemy.kernel.util.NamedObj
      ptolemy.domains.ct.kernel.ODESolver
          ptolemy.domains.ct.kernel.solver.ExplicitRK23Solver

All Implemented Interfaces:

java.io.Serializable, java.lang.Cloneable, Changeable, Debuggable, DebugListener, Derivable, ModelErrorHandler, MoMLExportable, Moveable, Nameable

public class ExplicitRK23Solver
extends ODESolver

This class implements the Explicit Runge-Kutta 2(3) ODE solving method. For an ODE of the form:

 dx/dt = f(x, t), x(0) = x0
 

it does the following:

 K0 = f(x(n), tn);
 K1 = f(x(n)+0.5*h*K0, tn+0.5*h);
 K2 = f(x(n)+0.75*h*K1, tn+0.75*h);
 x(n+1) = x(n)+(2/9)*h*K0+(1/3)*h*K0+(4/9)*h*K2;
 

, and error control:

 K3 = f(x(n+1), tn+h);
 LTE = h*[(-5.0/72.0)*K0 + (1.0/12.0)*K1 + (1.0/9.0)*K2 + (-1.0/8.0)*K3]
 

If the LTE is less than the error tolerance, then this step is considered successful, and the next integration step is predicted as:

 h' = 0.8*Math.pow((ErrorTolerance/LTE), 1.0/3.0)
 

This is a second order method, but uses a third order procedure to estimate the local truncation error.

Since:

Ptolemy II 0.2

Version:

$Id: ExplicitRK23Solver.java 57040 2010-01-27 20:52:32Z cxh $

Author:

Jie Liu, Haiyang Zheng

See Also:

Serialized Form

Accepted Rating:

Green (hyzheng)

Proposed Rating:

Green (hyzheng)

Nested Class Summary

Nested classes/interfaces inherited from class ptolemy.kernel.util.NamedObj

NamedObj.ContainedObjectsIterator

Field Summary

private static double[][]	_B
private static java.lang.String	_DEFAULT_NAME
private static double[]	_E
private static int	_order
private static double[]	_timeInc

Fields inherited from class ptolemy.kernel.util.NamedObj

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

Constructor Summary

ExplicitRK23Solver()
Construct a solver in the default workspace.

ExplicitRK23Solver(Workspace workspace)
Construct a solver in the given workspace.

Method Summary

protected void	_advanceModelTime() Override the method in the base abstract class to advance the model time.
void	fireStateTransitionActors() Fire state transition actors.
int	getAmountOfHistoryInformation() Return 0 to indicate that no history information is needed by this solver.
int	getIntegratorAuxVariableCount() Return 4 to indicate that four auxiliary variables are needed by this solver.
void	integratorFire(CTBaseIntegrator integrator) Fire the given integrator.
boolean	integratorIsAccurate(CTBaseIntegrator integrator) Return true if the integration is accurate for the given integrator.
double	integratorPredictedStepSize(CTBaseIntegrator integrator) Provide the predictedStepSize() method for the integrators under this solver.

Methods inherited from class ptolemy.domains.ct.kernel.ODESolver

_getRoundCount, _getSchedule, _incrementRoundCount, _isConverged, _makeSolverOf, _resetRoundCount, _setConverged, _voteForConverged, fireDynamicActors, getContainer, resolveStates

Methods inherited from class ptolemy.kernel.util.NamedObj

_addAttribute, _adjustOverride, _attachText, _cloneFixAttributeFields, _debug, _debug, _debug, _debug, _debug, _description, _exportMoMLContents, _getContainedObject, _getIndentPrefix, _isMoMLSuppressed, _markContentsDerived, _propagateExistence, _propagateValue, _recordDecoratedAttributes, _removeAttribute, _splitName, _stripNumericSuffix, _validateSettables, addChangeListener, addDebugListener, attributeChanged, attributeList, attributeList, attributeTypeChanged, clone, clone, containedObjectsIterator, deepContains, depthInHierarchy, description, description, event, executeChangeRequests, exportMoML, exportMoML, exportMoML, exportMoML, exportMoML, exportMoMLPlain, getAttribute, getAttribute, getAttributes, getChangeListeners, getClassName, getDecoratorAttribute, getDecoratorAttributes, getDerivedLevel, getDerivedList, getDisplayName, getElementName, getFullName, getModelErrorHandler, getName, getName, getPrototypeList, getSource, handleModelError, isDeferringChangeRequests, isOverridden, isPersistent, lazyContainedObjectsIterator, message, moveDown, moveToFirst, moveToIndex, moveToLast, moveUp, propagateExistence, propagateValue, propagateValues, removeChangeListener, removeDebugListener, requestChange, setClassName, setDeferringChangeRequests, setDerivedLevel, setDisplayName, setModelErrorHandler, setName, setPersistent, setSource, sortContainedObjects, toplevel, toString, uniqueName, validateSettables, workspace

Methods inherited from class java.lang.Object

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

Field Detail

_DEFAULT_NAME

private static final java.lang.String _DEFAULT_NAME

See Also:

Constant Field Values

_timeInc

private static final double[] _timeInc

_B

private static final double[][] _B

_E

private static final double[] _E

_order

private static final int _order

See Also:

Constant Field Values

Constructor Detail

ExplicitRK23Solver

public ExplicitRK23Solver()

Construct a solver in the default workspace. The solver is added to the list of objects in the workspace. Increment the version number of the workspace. The name of the solver is set to "CT_Runge_Kutta_2_3_Solver".

ExplicitRK23Solver

public ExplicitRK23Solver(Workspace workspace)

Construct a solver in the given workspace. If the workspace argument is null, use the default workspace. The director is added to the list of objects in the workspace. Increment the version number of the workspace. The name of the solver is set to "CT_Runge_Kutta_2_3_Solver".

Parameters:

workspace - Object for synchronization and version tracking.

Method Detail

fireStateTransitionActors

public void fireStateTransitionActors()
                               throws IllegalActionException

Fire state transition actors. Increment the round count. If the current round is the third round, set converged flag to true indicating a fixed-point states have been reached. Reset the round count if the current round is the last one.

Overrides:

fireStateTransitionActors in class ODESolver

Throws:

IllegalActionException - If thrown in the super class.

getAmountOfHistoryInformation

public final int getAmountOfHistoryInformation()

Return 0 to indicate that no history information is needed by this solver.

Specified by:

getAmountOfHistoryInformation in class ODESolver

Returns:

0.

getIntegratorAuxVariableCount

public final int getIntegratorAuxVariableCount()

Return 4 to indicate that four auxiliary variables are needed by this solver.

Specified by:

getIntegratorAuxVariableCount in class ODESolver

Returns:

4.

integratorFire

public void integratorFire(CTBaseIntegrator integrator)
                    throws IllegalActionException

Fire the given integrator. This method performs the ODE solving algorithm described in the class comment.

Specified by:

integratorFire in class ODESolver

Parameters:

integrator - The integrator of that calls this method.

Throws:

IllegalActionException - If there is no director, or can not read input, or can not send output.

integratorIsAccurate

public boolean integratorIsAccurate(CTBaseIntegrator integrator)

Return true if the integration is accurate for the given integrator. This estimates the local truncation error for that integrator and compare it with the error tolerance.

Specified by:

integratorIsAccurate in class ODESolver

Parameters:

integrator - The integrator of that calls this method.

Returns:

True if the integration is successful.

integratorPredictedStepSize

public double integratorPredictedStepSize(CTBaseIntegrator integrator)

Provide the predictedStepSize() method for the integrators under this solver. It uses the algorithm in the class comments to predict the next step size based on the current estimation of the local truncation error.

Specified by:

integratorPredictedStepSize in class ODESolver

Parameters:

integrator - The integrator of that calls this method.

Returns:

The next step size suggested by the given integrator.

_advanceModelTime

protected void _advanceModelTime()
                          throws IllegalActionException

Override the method in the base abstract class to advance the model time. The amount of the increment is decided by the number of the round counter and the current step size. In particular, at the first round, time is incremented by 1/2 of the current step size; at the second round, time is incremented by another 1/4 of the current step size; in the third round, time gets incremented by the last 1/4 of the current step size.

Overrides:

_advanceModelTime in class ODESolver

Throws:

IllegalActionException - If thrown in the super class or the model time can not be set.