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1.1
date	97.11.09.01.23.12;	author kowallik;	state Exp;
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desc
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1.1
log
@Initial revision
@
text
@// the number crunching class - separate thread that calculates
// position and velocity of pendulum and returns it


import java.util.*;
import java.lang.*;

class animation extends Thread
{

// variables used in the static rk4 routine have to be static   
   static double y[]=new double[2];
   static double damp, ext, phi, w, x;
   
// I need this to reset x0, v0 to initial values     
   double oldy[]=new double[2];

   double duration, xstart=0;
   int delay;
   
   Control_Win control;
   graphic out;
   P_Graph phase;
   T_Graph time;
   
   animation(Control_Win incontrol, double inxstart, double iny[], 
             double inphi, double indamp, 
             double inw, double inext, double induration, int indelay)
   {
      control = incontrol;
      y=iny;
      oldy=iny;
      damp=indamp;
      delay=indelay;
      duration=induration;
      phi=inphi;
      ext=inext;
      w=inw;
      out=control.out;
      phase=control.phase;
      time=control.time;
   }
   
   public void cleanup()
   {
      xstart=0;
      y=oldy;
   } 
   
   public void run()
   {
      int f_data=0;
      double k;
      for(x=xstart; x<duration; x+=0.05)
      {     
         for (k=x; k<=x+0.05; k+=0.005)
         {
            y=rk4(x, y, 0.005);
         }

         out.draw(y[0], y[1]);
         phase.draw(y[0], y[1]);
         time.draw(y[0]);
         
         try
         { 
            if (control.kill_thread == true)
            {
               System.out.println("kill thread");
               this.stop();
               
            }
            else
            {
               this.sleep(delay);
            }
         }catch (InterruptedException e)
         {}
      }
// draw a compressed version of the whole time plot at the end
      time.drawcom();
      this.cleanup();
   }    

// the Runge-Kutta routine
   
   static double[] rk4(double x, double y[], double step)
   {
       double h=step/2;
       double temp[]= new double[2];
       double k1[]= new double[2];
       double k2[]= new double[2];
       double k3[]= new double[2];
       double k4[]= new double[2];
       int i;         
             
       for (i=0;i<2;i++)   k1[i]=step*f(x, y, i);
       for (i=0;i<2;i++)   temp[i]=y[i]+0.5*k1[i];
       for (i=0;i<2;i++)  k2[i]=step*f(x+h, temp, i);
       for (i=0;i<2;i++)  temp[i]=y[i]+0.5*k2[i];
       for (i=0;i<2;i++)  k3[i]=step*f(x+h, temp, i);
       for (i=0;i<2;i++)  temp[i]=y[i]+k3[i];
       for (i=0;i<2;i++)  k4[i]=step*f(x+step, temp, i);
       for (i=0;i<2;i++) y[i]+=(k1[i]+2*k2[i]+2*k3[i]+k4[i])/6.0;
       return y;
   }

// the routine which returns the derivatives/definition of the system	
      
   static double f(double x, double y[], int i)
   {
      double tmp=0;
      if (i==0) tmp=(y[1]);
      if (i==1) tmp=(-Math.sin(y[0])-damp*y[1]+ext*Math.cos(w*x+phi));
      
      return tmp;
   }
}       
@