BALL::ConjugateGradientMinimizer Class Reference
[Energy Minimizer]

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

Inheritance diagram for BALL::ConjugateGradientMinimizer:


Classes
struct	Default
struct	Option
Public Types
Enums
enum	UpdateMethod { POLAK_RIBIERE = 1, FLETCHER_REEVES = 2, SHANNO = 3 }
Public Member Functions
Constructors and Destructors
	ConjugateGradientMinimizer ()
	ConjugateGradientMinimizer (ForceField &force_field)
	ConjugateGradientMinimizer (ForceField &force_field, SnapShotManager *ssm)
	ConjugateGradientMinimizer (ForceField &force_field, SnapShotManager *ssm, const Options &options)
	ConjugateGradientMinimizer (ForceField &force_field, const Options &options)
	ConjugateGradientMinimizer (const ConjugateGradientMinimizer &rhs)
virtual	~ConjugateGradientMinimizer ()
Assignments
const ConjugateGradientMinimizer &	operator= (const ConjugateGradientMinimizer &rhs)
Setup methods. They do all necessary preparations.
virtual bool	specificSetup ()
Accessors
void	setUpdateMethod (UpdateMethod method)
UpdateMethod	getUpdateMethod () const
virtual double	findStep ()
virtual void	updateDirection ()
virtual bool	minimize (Size iterations=0, bool resume=false)
Protected Attributes
Protected Attributes
LineSearch	line_search_
Gradient	unscaled_direction_
Size	number_of_atoms_
Size	updt_method_
bool	first_iter_
double	old_gtg_
vector< Vector3 >	a_i_
vector< Vector3 >	b_i_
vector< Vector3 >	p_t_
vector< Vector3 >	y_t_
vector< Vector3 >	p_i_
vector< Vector3 >	y_i_
double	D_1_
double	D_4_
Size	restart_frequency_
Size	last_restart_iter_

Detailed Description

A minimizer for geometry optimization based on different conjugate gradient (CG) algorithms. See

[1] Fletcher, R. and Reeves, C.M. "Function Minimization by Conjugate Gradients" Comp. J., 7, 149-154, 1964

[2] David Shanno "Conjugate Gradient Methods With Inexact Searches" Mathematics of Operations Research, Vol. 3, No. 3, August 1978, pp. 244-256

[3] S. Watowich et. al "A Stable Rapidly Converging Conjugate Gradient Method for Energy Minimization" Journal of Computational Chemistry, Vol. 9, No. 6, pp. 650-661 (1988)

[4] M.J.D. Powell "Convergence properties of algorithms for nonlinear optimization" Report No. DAMPT 1985/NA1, University of Cambridge, 1985

[5] D.F. Shanno "Globally convergent conjugate gradient algorithms" Mathematical Programming 33 (1985), pp. 61-67

Member Enumeration Documentation

enum BALL::ConjugateGradientMinimizer::UpdateMethod

The different conjugate gradient methods implemented.

See also:: updateDirection for details on the implementation and references

Enumerator:

POLAK_RIBIERE	Polak-Ribiere method
FLETCHER_REEVES	Fletcher-Reeves method
SHANNO	Shanno

Constructor & Destructor Documentation

BALL::ConjugateGradientMinimizer::ConjugateGradientMinimizer ( )

Default constructor.

BALL::ConjugateGradientMinimizer::ConjugateGradientMinimizer ( ForceField & force_field )

Constructor expecting a valid force field

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

Constructor expecting a valid force field and a snapshot manager

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

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

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

Constructor expecting a valid force field and options

BALL::ConjugateGradientMinimizer::ConjugateGradientMinimizer ( const ConjugateGradientMinimizer & rhs )

Copy constructor

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

Destructor.

Member Function Documentation

virtual double BALL::ConjugateGradientMinimizer::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.

UpdateMethod BALL::ConjugateGradientMinimizer::getUpdateMethod ( ) const

Returns the current method for updateDirection.

virtual bool BALL::ConjugateGradientMinimizer::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 ConjugateGradientMinimizer& BALL::ConjugateGradientMinimizer::operator= ( const ConjugateGradientMinimizer & rhs )

Assignment operator

void BALL::ConjugateGradientMinimizer::setUpdateMethod ( UpdateMethod method )

Set explicitly the criterion used for updateDirection. If the method is not recognized, this function fails.

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

Specific setup

Reimplemented from BALL::EnergyMinimizer.

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

Update the search direction. This method updates the search direction. It uses the different conjugate gradient caculations dependend on the options.

Reimplemented from BALL::EnergyMinimizer.

Member Data Documentation

vector<Vector3> BALL::ConjugateGradientMinimizer::a_i_ [protected]

Variable needed for the Shanno direction calculation

vector<Vector3> BALL::ConjugateGradientMinimizer::b_i_ [protected]

Variable needed for the Shanno direction calculation

double BALL::ConjugateGradientMinimizer::D_1_ [protected]

Variable needed for the Shanno direction calculation

double BALL::ConjugateGradientMinimizer::D_4_ [protected]

Variable needed for the Shanno direction calculation

bool BALL::ConjugateGradientMinimizer::first_iter_ [protected]

Is this the (initial) first iteration?

Size BALL::ConjugateGradientMinimizer::last_restart_iter_ [protected]

We count the iterations since the last restart. There are other necessities for a restart so the iteration counter may not coincide (by modulo) with the restart frequency.

LineSearch BALL::ConjugateGradientMinimizer::line_search_ [protected]

The line search

Size BALL::ConjugateGradientMinimizer::number_of_atoms_ [protected]

Number of movable atoms.

double BALL::ConjugateGradientMinimizer::old_gtg_ [protected]

$g^T \cdot g$ where $g$ is the gradient of the last iteration