LOCA::StepSize::Constant Class Reference

Constant step size control strategy More...

#include <LOCA_StepSize_Constant.H>

Inheritance diagram for LOCA::StepSize::Constant:

[legend]Collaboration diagram for LOCA::StepSize::Constant:[legend]List of all members.

Public Member Functions
	Constant (NOX::Parameter::List &params)
	Constructor.
virtual	~Constant ()
	Destructor.
virtual NOX::Abstract::Group::ReturnType	reset (NOX::Parameter::List &params)
	Reset parameters given above.
virtual NOX::Abstract::Group::ReturnType	compute (LOCA::Continuation::ExtendedGroup &curGroup, const LOCA::Continuation::ExtendedVector &predictor, const NOX::Solver::Generic &solver, const LOCA::Abstract::Iterator::StepStatus &stepStatus, const LOCA::Stepper &stepper, double &stepSize)
	Compute the step size as described above.
virtual NOX::Abstract::Group::ReturnType	compute (LOCA::MultiContinuation::ExtendedGroup &curGroup, const LOCA::MultiContinuation::ExtendedVector &predictor, const NOX::Solver::Generic &solver, const LOCA::Abstract::Iterator::StepStatus &stepStatus, const LOCA::NewStepper &stepper, double &stepSize)
	Compute the step size as described above.
virtual double	getPrevStepSize () const
	Returns previous step size.
virtual double	getStartStepSize () const
	Returns initial step size.
Protected Member Functions
virtual NOX::Abstract::Group::ReturnType	clipStepSize (double &stepSize)
	Clip the computed step size to the bounds given by the maximum and minimum step sizes.
Protected Attributes
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.

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Detailed Description

Constant step size control strategy

This class implements a roughly constant step size control strategy. If the previous step was sucessful, the new step size is set equal to the old, otherwise the step size is cut by a supplied factor. Once a sucessful step is made, the step size is increased by a supplied factor until the initial step size is reached.

This class also incorporates rescaling of the continuation parameter when calculating a step size (common in arc-length continuation). For the first continuation step, the step size is chosen so that step size times the parameter component of the predictor is equal to the initial step size. From then on, the step size is multiplied by the step size scale factor (see LOCA::Continuation::ExtendedGroup) which incorporates rescaling of the continuation parameter.

The parameters used by this class supplied in the constructor or reset method are:

• "Max Step Size" - Largest valid step size (Default 1.0e+12)
• "Min Step Size" - Smallest valid step size (Default 1.0e-12)
• "Initial Step Size" - Initial step size (Default 1.0)
• "Failed Step Reduction Factor" - Factor by which step size is reduced after a failed step. (Default 0.5)
• "Successful Step Increase Factor" - Factor by which step size is increased after a successful step when the step size is smaller than the initial step size. (Default 1.26 = )

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Member Function Documentation

NOX::Abstract::Group::ReturnType LOCA::StepSize::Constant::clipStepSize (  double &  stepSize  )  [protected, virtual]

Clip the computed step size to the bounds given by the maximum and minimum step sizes. Returns NOX::Abstract::Group::Failed if the computed step size is smaller than the minimum step size

NOX::Abstract::Group::ReturnType LOCA::StepSize::Constant::compute (  LOCA::MultiContinuation::ExtendedGroup &  curGroup, const LOCA::MultiContinuation::ExtendedVector &  predictor, const NOX::Solver::Generic &  solver, const LOCA::Abstract::Iterator::StepStatus &  stepStatus, const LOCA::NewStepper &  stepper, double &  stepSize )  [virtual]

Compute the step size as described above. Returns NOX::Abstract::Group::Failed if the computed step size is smaller than the minimum step size Implements LOCA::StepSize::Generic. Reimplemented in LOCA::StepSize::Adaptive.

NOX::Abstract::Group::ReturnType LOCA::StepSize::Constant::compute (  LOCA::Continuation::ExtendedGroup &  curGroup, const LOCA::Continuation::ExtendedVector &  predictor, const NOX::Solver::Generic &  solver, const LOCA::Abstract::Iterator::StepStatus &  stepStatus, const LOCA::Stepper &  stepper, double &  stepSize )  [virtual]

Compute the step size as described above. Returns NOX::Abstract::Group::Failed if the computed step size is smaller than the minimum step size Implements LOCA::StepSize::Generic. Reimplemented in LOCA::StepSize::Adaptive.

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

• LOCA_StepSize_Constant.H
• LOCA_StepSize_Constant.C

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