Adaptive step size control strategy More...

#include <LOCA_StepSize_Adaptive.H>

Inheritance diagram for LOCA::StepSize::Adaptive:

Collaboration diagram for LOCA::StepSize::Adaptive:

Public Member Functions
	Adaptive (const Teuchos::RCP< LOCA::GlobalData > &global_data, const Teuchos::RCP< LOCA::Parameter::SublistParser > &topParams, const Teuchos::RCP< Teuchos::ParameterList > &stepsizeParams)
	Constructor.

virtual	~Adaptive ()
	Destructor.

virtual NOX::Abstract::Group::ReturnType	computeStepSize (LOCA::MultiContinuation::AbstractStrategy &curGroup, const LOCA::MultiContinuation::ExtendedVector &predictor, const NOX::Solver::Generic &solver, const LOCA::Abstract::Iterator::StepStatus &stepStatus, const LOCA::Abstract::Iterator &stepper, double &stepSize)
	Compute the step size as described above. More...

Public Member Functions inherited from LOCA::StepSize::Constant
	Constant (const Teuchos::RCP< LOCA::GlobalData > &global_data, const Teuchos::RCP< LOCA::Parameter::SublistParser > &topParams, const Teuchos::RCP< Teuchos::ParameterList > &stepsizeParams)
	Constructor.

virtual	~Constant ()
	Destructor.

virtual double	getPrevStepSize () const
	Returns previous step size.

virtual double	getStartStepSize () const
	Returns initial step size.

Public Member Functions inherited from LOCA::StepSize::AbstractStrategy
	AbstractStrategy ()
	Constructor.

virtual	~AbstractStrategy ()
	Destructor.

Protected Attributes
double	agrValue
	Stores the aggressiveness factor .

double	maxNonlinearSteps
	Maximum number of nonlinear iterations.

Protected Attributes inherited from LOCA::StepSize::Constant
Teuchos::RCP< LOCA::GlobalData >	globalData
	Global data.

double	maxStepSize
	Maximum step size.

double	minStepSize
	Minimum step size.

double	startStepSize
	Initial step size.

double	failedFactor
	Factor by which step size is reduced after a failed step.

double	successFactor
	Factor by which step size is increased after a successful step.

double	prevStepSize
	Previous step size.

bool	isFirstStep
	Flag indicating if this is the first step.

Additional Inherited Members
Protected Member Functions inherited from LOCA::StepSize::Constant
virtual NOX::Abstract::Group::ReturnType	clipStepSize (double &stepSize)
	Clip the computed step size to the bounds given by the maximum and minimum step sizes. More...

Detailed Description

Adaptive step size control strategy

This class implements an adaptive step size control strategy derived from the strategy implemented in the LOCA::StepSize::Constant class. If the previous step was unsucessful, the step size is cut in half as in the constant strategy, but if the step was sucessful this strategy increases the step size based on the number of nonlinear solver iterations required in the previous step. In particular, the new step size $\Delta s_{new}$ is given by

$\Delta s_{new} = \Delta s_{old}\left(1 + a\left(\frac{N_{max} - N}{N_{max}}\right)^2\right)$

where $a\in[0,1]$ is an aggressiveness factor, $N$ is the number of nonlinear solver iterations in the previous step, and $N_{max}$ is the maximum number of nonlinear solver iterations.

The parameters used by this class supplied in the constructor are the same as used by the Constant class in addition to:

"Aggressiveness" - Aggressiveness factor (Default 0.5)

Member Function Documentation

NOX::Abstract::Group::ReturnType LOCA::StepSize::Adaptive::computeStepSize	(	LOCA::MultiContinuation::AbstractStrategy &	curGroup,
		const LOCA::MultiContinuation::ExtendedVector &	predictor,
		const NOX::Solver::Generic &	solver,
		const LOCA::Abstract::Iterator::StepStatus &	stepStatus,
		const LOCA::Abstract::Iterator &	stepper,
		double &	stepSize
	)

virtual

Compute the step size as described above.

Parameters

curGroup	[in] Current continuation group
predictor	[in] Current predictor direction
solver	[in] Solver from previous step
stepStatus	[in] Status of previous step
stepper	[in] Stepper
stepSize	[out] Computed step size

Returns: ReturnType code indicating success or failure Returns NOX::Abstract::Group::Failed if the computed step size is smaller than the minimum step size

Reimplemented from LOCA::StepSize::Constant.

References LOCA::StepSize::Constant::failedFactor, NOX::Solver::Generic::getNumIterations(), LOCA::Extended::Vector::getScalar(), LOCA::MultiContinuation::AbstractStrategy::getStepSizeScaleFactor(), LOCA::StepSize::Constant::isFirstStep, LOCA::StepSize::Constant::maxStepSize, LOCA::StepSize::Constant::minStepSize, LOCA::StepSize::Constant::startStepSize, and LOCA::Abstract::Iterator::Unsuccessful.

The documentation for this class was generated from the following files:

LOCA_StepSize_Adaptive.H
LOCA_StepSize_Adaptive.C

Public Member Functions

Protected Attributes

Additional Inherited Members

Detailed Description

Member Function Documentation