org.gicentre.utils.network.traer.physics

Class RungeKuttaIntegrator

java.lang.Object

org.gicentre.utils.network.traer.physics.Integrator

org.gicentre.utils.network.traer.physics.RungeKuttaIntegrator

Direct Known Subclasses:

SettlingRungeKuttaIntegrator

public class RungeKuttaIntegrator
extends Integrator

Class capable of performing Runge Kutta integration. Compared to the Euler integrators, this one is slower but is more stable.

Version:

3.4, 5th February, 2016.

Author:

Carl Pearson, Jeffrey Traer Bernstein and minor modifications by Jo Wood.

Nested Class Summary

Nested classes/interfaces inherited from class org.gicentre.utils.network.traer.physics.Integrator

Integrator.METHOD

Field Summary

Fields inherited from class org.gicentre.utils.network.traer.physics.Integrator

s

Constructor Summary

Constructors

Constructor and Description
RungeKuttaIntegrator(ParticleSystem s) Sets up the integrator to be used by the given particle system.

Method Summary

Modifier and Type	Method and Description
protected void	allocateParticles() Instantiates the original positions and velocities of the particles.
protected static Function<Particle,?>	kApplier(java.util.Map<Particle,Vector3D> kForces, java.util.Map<Particle,Vector3D> kVelocities, java.util.Map<Particle,Vector3D> originalPositions, java.util.Map<Particle,Vector3D> originalVelocities, float deltaT) Provides the function that applies the single increment of the particles' positions and velocities.
protected static Function<Particle,?>	kFunctor(java.util.Map<Particle,Vector3D> kForces, java.util.Map<Particle,Vector3D> kVelocities) Provides the function capable of performing the integration.
RungeKuttaIntegrator	step(float deltaT) Performs the incrementing of the particles' positions and velocities over the given time step.
protected Function<Particle,?>	updater(java.util.Map<Particle,Vector3D> k1f, java.util.Map<Particle,Vector3D> k1v, java.util.Map<Particle,Vector3D> k2f, java.util.Map<Particle,Vector3D> k2v, java.util.Map<Particle,Vector3D> k3f, java.util.Map<Particle,Vector3D> k3v, java.util.Map<Particle,Vector3D> k4f, java.util.Map<Particle,Vector3D> k4v, java.util.Map<Particle,Vector3D> oPos, java.util.Map<Particle,Vector3D> oVel, float deltaT) Provides the function that updates the particles in the system.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

RungeKuttaIntegrator

public RungeKuttaIntegrator(ParticleSystem s)

Sets up the integrator to be used by the given particle system.

Parameters:

s - Particle system upon which to perform the integration.

Method Detail

kFunctor

protected static final Function<Particle,?> kFunctor(java.util.Map<Particle,Vector3D> kForces,
                                                     java.util.Map<Particle,Vector3D> kVelocities)

Provides the function capable of performing the integration.

Parameters:

kForces - Forces to be applied to particles during integration.

kVelocities - Velocities of particles.

Returns:

The function that performs the integration.

kApplier

protected static final Function<Particle,?> kApplier(java.util.Map<Particle,Vector3D> kForces,
                                                     java.util.Map<Particle,Vector3D> kVelocities,
                                                     java.util.Map<Particle,Vector3D> originalPositions,
                                                     java.util.Map<Particle,Vector3D> originalVelocities,
                                                     float deltaT)

Provides the function that applies the single increment of the particles' positions and velocities.

Parameters:

kForces - Forces associated with the particles/

kVelocities - Velocities of the particles.

originalPositions - The original positions of the particles before integration.

originalVelocities - The original velocities of the particles before integration.

deltaT - Time step over which to move the particles.

Returns:

The function that increments the particles.

updater

protected Function<Particle,?> updater(java.util.Map<Particle,Vector3D> k1f,
                                       java.util.Map<Particle,Vector3D> k1v,
                                       java.util.Map<Particle,Vector3D> k2f,
                                       java.util.Map<Particle,Vector3D> k2v,
                                       java.util.Map<Particle,Vector3D> k3f,
                                       java.util.Map<Particle,Vector3D> k3v,
                                       java.util.Map<Particle,Vector3D> k4f,
                                       java.util.Map<Particle,Vector3D> k4v,
                                       java.util.Map<Particle,Vector3D> oPos,
                                       java.util.Map<Particle,Vector3D> oVel,
                                       float deltaT)

Provides the function that updates the particles in the system.

Parameters:

k1f - K1 force.

k1v - K1 velocity.

k2f - K2 force.

k2v - K2 velocity.

k3f - K3 force.

k3v - K3 velocity.

k4f - K4 force.

k4v - K4 velocity.

oPos - Original position.

oVel - Original velocity.

deltaT - Change in time units.

Returns:

Function that updates the particle positions.

allocateParticles

protected final void allocateParticles()

Instantiates the original positions and velocities of the particles. This has the side-effect of clearing all forces on particles.

step

public RungeKuttaIntegrator step(float deltaT)

Performs the incrementing of the particles' positions and velocities over the given time step.

Specified by:

step in class Integrator

Parameters:

deltaT - Time step over which to update the particles.

Returns:

The integrator that updates the system.