net.java.dev.joode.stepper
Class RungeKuttaOrder4Stepper

java.lang.Object
  net.java.dev.joode.stepper.RungeKuttaOrder4Stepper

All Implemented Interfaces:

StepperFunction

public class RungeKuttaOrder4Stepper
extends java.lang.Object
implements StepperFunction

Steps the world forward in time using the Runge-Kutter order four intergration This calls the LCP algorithm 4 times, but produces very accurate results, so calling it with large stepsizes is exceptable. Error of order h^5 Formula is k1 = hf(x0, t0) k2 = hf(x0+k1/2, t0 + h/2) k3 = hf(x0+k2/2, t0 + h/2) k4 = hf(x0+k3, t0+h) x(t0+h) = x0 + k1/6 + k2/3 + k3/3 + k4/6 OR xn+1 = xn + h/6 (a + 2 b + 2 c + d) where a = f (0 , xn) b = f (h/2, xn + h/2 a) c = f (h/2, xn + h/2 b) d = f (h, xn + h c) k1 is the slope at the beginning of the interval; k2 is the slope at the midpoint of the interval, using slope k1 to determine the value of y at the point tn + h/2 using Euler's method; k3 is again the slope at the midpoint, but now using the slope k2 to determine the y-value; k4 is the slope at the end of the interval, with its y-value determined using k3.

Author:

Tom Larkworthy

Field Summary

static RungeKuttaOrder4Stepper	INSTANCE
static Joint.Info2	Jinfo
static boolean	REPORT_ERROR
static float	STEP_SIZE the small step size that the stepper uses to estimate the acceleration curve at a point in time

Fields inherited from interface net.java.dev.joode.stepper.StepperFunction

EULER, RK4

Method Summary

void	step(World world, Body[] body, int nb, Joint[] joint, int nj, float stepsize) steps the ISLAND of bodies one step using the mid point method

Methods inherited from class java.lang.Object

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

Field Detail

REPORT_ERROR

public static final boolean REPORT_ERROR

See Also:

Constant Field Values

INSTANCE

public static final RungeKuttaOrder4Stepper INSTANCE

STEP_SIZE

public static float STEP_SIZE

the small step size that the stepper uses to estimate the acceleration curve at a point in time

Jinfo

public static final Joint.Info2 Jinfo

Method Detail

step

public void step(World world,
                 Body[] body,
                 int nb,
                 Joint[] joint,
                 int nj,
                 float stepsize)

steps the ISLAND of bodies one step using the mid point method

Specified by:

step in interface StepperFunction