ptolemy.domains.ct.kernel.solver
Class BackwardEulerSolver

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

All Implemented Interfaces:

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

public class BackwardEulerSolver
extends FixedStepSolver

The Backward Euler ODE solver. For an ODE

 x' = f(x, u, t), x(0) = x0
 

This solver uses the following formula to solve it:

 x(t+h) = x(t) + h*x'(t+h)
 

where x(t) is the current state, x(t+h) is the next state, h is the step size, and x'(t+h) is the derivative of x at t+h. The formula above is an algebraic equation, and this solver uses fixed point iteration to solve it.

This solver does not perform step size control even when the states do not converge after the maximum number of iterations is reached. However, CT directors may try to reduce step size. This solver does not give suggestions on choosing step size.

Since:

Ptolemy II 0.2

Version:

$Id: BackwardEulerSolver.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 java.lang.String

_DEFAULT_NAME Name of this Solver.

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

BackwardEulerSolver()
Construct a solver in the default workspace with the name "CT_Backward_Euler_Solver".

BackwardEulerSolver(Workspace workspace)
Construct a solver in the given workspace with the name "CT_Backward_Euler_Solver".

Method Summary

void	integratorFire(CTBaseIntegrator integrator) Fire the integrator to resolve states.
boolean	resolveStates() Return true if the resolved states have converged.

Methods inherited from class ptolemy.domains.ct.kernel.solver.FixedStepSolver

_advanceModelTime, fireDynamicActors, fireStateTransitionActors, getAmountOfHistoryInformation, getIntegratorAuxVariableCount, integratorIsAccurate, integratorPredictedStepSize

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

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

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

Name of this Solver.

See Also:

Constant Field Values

Constructor Detail

BackwardEulerSolver

public BackwardEulerSolver()

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

BackwardEulerSolver

public BackwardEulerSolver(Workspace workspace)

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

Parameters:

workspace - Object for synchronization and version tracking

Method Detail

integratorFire

public void integratorFire(CTBaseIntegrator integrator)
                    throws IllegalActionException

Fire the integrator to resolve states. Vote false for convergence if a fixed-point solution is not found.

Specified by:

integratorFire in class ODESolver

Parameters:

integrator - The integrator to be fired.

Throws:

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

resolveStates

public boolean resolveStates()
                      throws IllegalActionException

Return true if the resolved states have converged. Return false if states have not converged but the number of iterations reaches the maxIterations number. Meanwhile, the round count is reset.

Overrides:

resolveStates in class ODESolver

Returns:

True if the resolved states have converged.

Throws:

IllegalActionException - Not thrown in this base class.