BALL::StrangLBFGSMinimizer Class Reference
[Energy Minimizer]

#include <BALL/MOLMEC/MINIMIZATION/strangLBFGS.h>

Inheritance diagram for BALL::StrangLBFGSMinimizer:


Classes
struct	Default
struct	Option
Public Member Functions
Constructors and Destructors
	StrangLBFGSMinimizer ()
	StrangLBFGSMinimizer (ForceField &force_field)
	StrangLBFGSMinimizer (ForceField &force_field, SnapShotManager *ssm)
	StrangLBFGSMinimizer (ForceField &force_field, SnapShotManager *ssm, const Options &options)
	StrangLBFGSMinimizer (ForceField &force_field, const Options &options)
	StrangLBFGSMinimizer (const StrangLBFGSMinimizer &rhs)
virtual	~StrangLBFGSMinimizer ()
Assignments
const StrangLBFGSMinimizer &	operator= (const StrangLBFGSMinimizer &rhs)
Setup methods. They do all necessary preparations.
virtual bool	specificSetup ()
Accessors
void	setMaxNumOfStoredVectPairs (Size num)
Size	getMaxNumOfStoredVectPairs () const
void	setImprovedFlag (bool flag)
bool	getImprovedFlag () const
virtual double	findStep ()
virtual void	updateDirection ()
virtual bool	minimize (Size iterations=0, bool resume=false)
Protected Attributes
Protected Attributes
LineSearch	line_search_
bool	first_iter_
Size	number_of_atoms_
Size	max_num_of_vect_pairs_
Size	curr_num_of_vect_pairs_
bool	improved_
vector< float >	rho_
vector< Vector3 >	stored_s_
vector< Vector3 >	stored_y_
vector< float >	work_val_
Size	index_of_free_vect_
std::vector< Vector3 >	initial_atoms_

Detailed Description

Limited-memory BFGS minimizer based on the Strang recurrence. A minimizer for geometry optimization based on the limited-memory BFGS method proposed in

[1] Nocedal J.: Updating quasi-Newton matrices with limited storage. Math. Comp. 35 (1980) 773-782.

[2] Liu D.C., Nocedal J.: On the limited memory BFGS method for large scale optimization. Math. Programming 45 (1989) 503-528.

If the 'improved' option is set, ideas proposed in

[3] Mehiddin Al-Baali: Improved Hessian approximations for the limited memory BFGS method. Numerical Algorithms 22 (1999) 99-112

are adopted.

Constructor & Destructor Documentation

BALL::StrangLBFGSMinimizer::StrangLBFGSMinimizer ( )

Default constructor.

BALL::StrangLBFGSMinimizer::StrangLBFGSMinimizer ( ForceField & force_field )

Constructor expecting a valid force field

BALL::StrangLBFGSMinimizer::StrangLBFGSMinimizer	(	ForceField &	force_field,
		SnapShotManager *	ssm
	)

Constructor expecting a valid force field and a snapshot manager

BALL::StrangLBFGSMinimizer::StrangLBFGSMinimizer	(	ForceField &	force_field,
		SnapShotManager *	ssm,
		const Options &	options
	)

Constructor expecting a valid force field, a snapshot manager and options

BALL::StrangLBFGSMinimizer::StrangLBFGSMinimizer	(	ForceField &	force_field,
		const Options &	options
	)

Constructor expecting a valid force field and options

BALL::StrangLBFGSMinimizer::StrangLBFGSMinimizer ( const StrangLBFGSMinimizer & rhs )

Copy constructor

virtual BALL::StrangLBFGSMinimizer::~StrangLBFGSMinimizer ( ) [virtual]

Destructor.

Member Function Documentation

virtual double BALL::StrangLBFGSMinimizer::findStep ( ) [virtual]

Calculate the next step. First, this method updates the model. Second, it performs a line search along the calculated direction afterwards.

Returns:: double $\geq 0$ if the line search found an acceptable solution, otherwise -1.

See also:: EnergyMinimizer::findStep

Reimplemented from BALL::EnergyMinimizer.

bool BALL::StrangLBFGSMinimizer::getImprovedFlag ( ) const

Return the improved flag

Size BALL::StrangLBFGSMinimizer::getMaxNumOfStoredVectPairs ( ) const

Return the maximum number of stored vector pairs

virtual bool BALL::StrangLBFGSMinimizer::minimize	(	Size	iterations = `0`,
		bool	resume = `false`
	)			`[virtual]`

Minimize the energy of the system. This method executes at most iterations minimization steps. If the number of iterations is not given, the number specified in the options is taken.

Parameters:

	iterations	the maximum number of iterations
	resume	true to resume a previous run

See also:: EnergyMinimizer::minimize

Reimplemented from BALL::EnergyMinimizer.

const StrangLBFGSMinimizer& BALL::StrangLBFGSMinimizer::operator= ( const StrangLBFGSMinimizer & rhs )

Assignment operator

void BALL::StrangLBFGSMinimizer::setImprovedFlag ( bool flag )

Set the improved flag

void BALL::StrangLBFGSMinimizer::setMaxNumOfStoredVectPairs ( Size num )

Set the maximum number of stored vector pairs

virtual bool BALL::StrangLBFGSMinimizer::specificSetup ( ) [virtual]

Specific setup

Reimplemented from BALL::EnergyMinimizer.

virtual void BALL::StrangLBFGSMinimizer::updateDirection ( ) [virtual]

Update the stored vector pairs, either by adding a new pair or if there is no space left by replacing the oldest pair. Compute the search direction afterwards by using the Strang recurrence formula (optional: with an improvement idea of Al-Baali).

Reimplemented from BALL::EnergyMinimizer.