Hi there,
I'm new to Java and working on a project to integrate some ODEs. I'm
having issues knowing how to work with the event handler. My ODE class
looks like:
public class DipoleODEimplements FirstOrderDifferentialEquations {
public int getDimension() {
return 6; }
public void computeDerivatives(double t, double[] y, double[] yDot) {
double r = y[0]; double r2 = r * r; double r3 = r2 * r; double r4 = r3
* r; double theta = y[1]; double phi = y[2]; double sin_phi = Math.sin(phi);
double cos_phi = Math.cos(phi); double pr = y[3]; double ptheta = y[4]; double
ptheta2 = ptheta * ptheta; double pphi = y[5]; double cos2 = Math.cos(phi -2 *
theta); double sin2 = Math.sin(phi -2 * theta); yDot[0] = pr; yDot[1] = ptheta
/ r2; yDot[2] =10 * pphi; yDot[3] = ptheta2 / r3 - (cos_phi +3 * cos2) / (4 *
r4); yDot[4] = sin2 / (2 * r3); yDot[5] = -(sin_phi +3 * sin2) / (12 * r3); }
}
When the y[0] value gets below 1.0, I'd like to change the y[3] value
and the continue the integration. Basically I'm looking for a ball to
bounce off another one. The integration gets stuck though and I can't
seem to get things bouncing. Here's my event handler, too:
EventHandler handler =new EventHandler() {
@Override public void init(double t0, double[] y0, double t) {
}
@Override public double g(double t, double[] y) {
return y[0] -1.0; }
@Override public ActioneventOccurred(double t, double[] y, boolean
increasing) {
return Action.RESET_STATE; }
@Override public void resetState(double t, double[] y) {
y[3] *= -1.0; }
};
And adding it to the integrator:
dp853.addEventHandler(handler, 50.0, 1e-6, 100);
Thanks for the help,
--
Bo Johnson
(801) 503-2043
