TestOdeNd

package odend;

import java.awt.*;

/**
 * integrate the ODE of a damped peridically driven pendulum<br>
 * plots results at fixed time steps
 */
public class TestOdeNd {
  public static void main(String[] args) {
    
    // set up the ODE
    double t0 = 0.0;
    double phi0 = Math.PI*500.0/1000.0;
    double phidot0 = 0.0;
    PendelErzwODE ode = new PendelErzwODE(phi0, phidot0, t0);
    ode.setA(115.0/100.0);
    
    // set up the solver 
    double dt = 1.0/100.0;
    double tEnd = 200.0;
    ODESolver solv = new ODESolverRK4(ode);
    
    // arrays to store the results
    int maxsteps = (int) Math.round(tEnd / dt);
    double[] t = new double[maxsteps + 1];
    double[] s = new double[maxsteps + 1];
    
    // loop over time steps
    for (int i = 0; i < maxsteps; i++) {
      t[i] = solv.t;
      s[i] = solv.x.get(0,0);
      solv.nextStep(dt);
    }
    t[maxsteps] = solv.t;
    s[maxsteps] = solv.x.get(0,0);
    
    // display the result
    Frame frame = new SimplePlot("TestOdeNd", 500, 300, t, s);
  }
}