Integrator Class Reference

An Integrator defines a method for simulating a System by integrating the equations of motion. More...

#include <Integrator.h>

Inheritance diagram for Integrator:

Public Member Functions
	Integrator ()
virtual	~Integrator ()
double	getStepSize () const
	Get the size of each time step, in picoseconds.
void	setStepSize (double size)
	Set the size of each time step, in picoseconds.
double	getConstraintTolerance () const
	Get the distance tolerance within which constraints are maintained, as a fraction of the constrained distance.
void	setConstraintTolerance (double tol)
	Set the distance tolerance within which constraints are maintained, as a fraction of the constrained distance.
virtual void	step (int steps)=0
	Advance a simulation through time by taking a series of time steps.

Protected Member Functions
virtual void	initialize (ContextImpl &context)=0
	This will be called by the Context when it is created.
virtual void	cleanup ()
	This will be called by the Context when it is destroyed to let the Integrator do any necessary cleanup.
virtual std::vector< std::string >	getKernelNames ()=0
	Get the names of all Kernels used by this Integrator.
virtual void	stateChanged (State::DataType changed)
	This will be called by the Context when the user modifies aspects of the context state, such as positions, velocities, or parameters.
virtual double	computeKineticEnergy ()=0
	Compute the kinetic energy of the system at the current time.

Protected Attributes
ContextImpl *	context
Context *	owner

Friends
class	Context
class	ContextImpl

Detailed Description

An Integrator defines a method for simulating a System by integrating the equations of motion.

This is an abstract class. Subclasses define particular integration methods.

Each Integrator object is bound to a particular Context which it integrates. This connection is specified by passing the Integrator as an argument to the constructor of the Context.

Constructor & Destructor Documentation

Integrator

(

)

virtual ~Integrator ( )

virtual

Member Function Documentation

virtual void cleanup ( )

inlineprotectedvirtual

This will be called by the Context when it is destroyed to let the Integrator do any necessary cleanup.

It will also get called again if the application calls reinitialize() on the Context.

Reimplemented in CustomIntegrator, VariableLangevinIntegrator, BrownianIntegrator, LangevinIntegrator, VariableVerletIntegrator, and VerletIntegrator.

virtual double computeKineticEnergy ( )

protectedpure virtual

Compute the kinetic energy of the system at the current time.

This may be different from simply mv²/2. For example, a leapfrog integrator will store velocities offset by half a step, but the kinetic energy should be computed at the current time, not delayed by half a step.

Implemented in CustomIntegrator, VariableLangevinIntegrator, BrownianIntegrator, LangevinIntegrator, VariableVerletIntegrator, and VerletIntegrator.

double getConstraintTolerance ( ) const

inline

Get the distance tolerance within which constraints are maintained, as a fraction of the constrained distance.

virtual std::vector<std::string> getKernelNames ( )

protectedpure virtual

Get the names of all Kernels used by this Integrator.

Implemented in CustomIntegrator, VariableLangevinIntegrator, BrownianIntegrator, LangevinIntegrator, VariableVerletIntegrator, and VerletIntegrator.

double getStepSize ( ) const

inline

Get the size of each time step, in picoseconds.

If this integrator uses variable time steps, the size of the most recent step is returned.

Returns

the step size, measured in ps

virtual void initialize ( ContextImpl &  context )

protectedpure virtual

This will be called by the Context when it is created.

It informs the Integrator of what context it will be integrating, and gives it a chance to do any necessary initialization. It will also get called again if the application calls reinitialize() on the Context.

Implemented in CustomIntegrator, VariableLangevinIntegrator, BrownianIntegrator, LangevinIntegrator, VariableVerletIntegrator, and VerletIntegrator.

void setConstraintTolerance ( double  tol )

inline

Set the distance tolerance within which constraints are maintained, as a fraction of the constrained distance.

void setStepSize ( double  size )

inline

Set the size of each time step, in picoseconds.

If this integrator uses variable time steps, the effect of calling this method is undefined, and it may simply be ignored.

Parameters

size	the step size, measured in ps

virtual void stateChanged ( State::DataType  changed )

inlineprotectedvirtual

This will be called by the Context when the user modifies aspects of the context state, such as positions, velocities, or parameters.

This gives the Integrator a chance to discard cached information. This is only called when the user modifies information using methods of the Context object. It is not called when a ForceImpl object modifies state information in its updateContextState() method (unless the ForceImpl calls a Context method to perform the modification).

Parameters

changed

this specifies what aspect of the Context was changed

Reimplemented in CustomIntegrator.

virtual void step ( int  steps )

pure virtual

Advance a simulation through time by taking a series of time steps.

Parameters

steps

the number of time steps to take

Implemented in CustomIntegrator, VariableLangevinIntegrator, BrownianIntegrator, LangevinIntegrator, VariableVerletIntegrator, and VerletIntegrator.

Friends And Related Function Documentation

friend class Context

friend

friend class ContextImpl

friend

Member Data Documentation

ContextImpl* context

protected

Context* owner

protected

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

• Integrator.h