//kohon.java
// applet framework
// for demonstrating a square kohonen Neural network
// (c) 1998 Robert W. Harrison

import java.lang.*;
import java.applet.*;
import java.awt.*;
import java.util.*;

public class k2 extends Applet implements Runnable{

  Thread lz = null;

  public boolean handleEvent(Event e)
    {
        if( e.id == Event.WINDOW_DESTROY)// this is needed for graceful close
          {
            System.exit(0);
          }
          return super.handleEvent(e);
    }
  public void start()
  { if(lz == null ) lz = new Thread(this);
    lz.start();
  }
  public void stop()
  {
    lz.stop();
    lz = null; // force gc
  }

  public static int NPoints;
  public void init()
  {

        String temp;
        Integer itemp;
        temp = getParameter("npoints");
        if( temp == null){ NPoints = 25;}
        else{ itemp = new Integer(temp); NPoints = itemp.intValue();}
  //      if( NPoints > 100) NPoints = 100;

  }


  public void run()
  {
    Graphics g;
    rrandom rnx = new rrandom((long)10134);
    rrandom rny = new rrandom((long)31459265);
    int i,j,imin,jmax,ii,imax;
    float x[] = new float[NPoints],y[] = new float[NPoints],r,xr,yr;
    float xo[] = new float[NPoints],yo[] = new float[NPoints];
    float dx,dy;
    float rmin;
    float damp,kern;
    Color red,green;

    g= this.getGraphics();
    red =  new Color(255,0,0);
    green =  new Color(0,255,0);
    jmax = NPoints;
    if( jmax > 100) jmax = 100;
    imax = NPoints/4;

    damp = (float)1.0;
    for( i=0; i< NPoints; i++)
    { x[i] = rnx.nextFloat();y[i] = rny.nextFloat();}

    for(;;)// forever
    {
        for(j=0; j< NPoints; j++)
        { xo[j] = x[j]; yo[j] = y[j];}

        damp = damp + (float)0.1;
        // update the points
        for( j=0; j< jmax; j++){
        xr = rnx.nextFloat(); yr = rny.nextFloat();
        rmin =(xr-x[0])*(xr-x[0]) + (yr-y[0])*(yr-y[0]);
        imin = 0;
        for( i=1; i< NPoints; i++)
            {
                r = (xr-x[i])*(xr-x[i]) + (yr-y[i])*(yr-y[i]);
                if( r < rmin)
                { rmin = r; imin = i;}
            }
        // now move the closest and his neighbors
	if( damp*4 > imax) damp = imax/4;
          for( i=0; i< imax; i++)
        {

   //         kern = (float)0.5/(damp*i + (float)1.);
              kern = (float)0.5*(imax-i*damp)/(imax);
//              if( kern < (float)0.0) kern = (float)0.0;
 	if( kern < (float)0.0) break;
            ii = imin -i;
            if( ii > -1 ){
            dx = xr-x[ii]; dy = yr-y[ii];
            x[ii] += kern*dx;
            y[ii] += kern*dy;
            }
            ii = imin +i;
            if( ii <NPoints ){
            dx = xr-x[ii]; dy = yr-y[ii];
            x[ii] += kern*dx;
            y[ii] += kern*dy;
            }


        }



     }

        plot( g,xo,yo,NPoints,red);
        plot( g,x,y,NPoints,green);

       try{ lz.sleep(10);} catch( InterruptedException e){;}

    }
  }

  public void plot( Graphics g,float x[],float y[], int np, Color c)
  {
    int sx,sy,i;
   // float scx,scy;
    //float x,dx;
    sx = size().width; sy = size().height;
  //  scx = (float)sx/(float)2.; scy = (float)sy/(float)2.;
    /* adjusted size 1/2 original for poincare map next to it */
    g.setColor( c);

    for( i=1; i< np; i++)
    {
        g.drawLine( (int)(x[i-1]*sx), (int)(y[i-1]*sy),
                    (int)(x[i]*sx), (int)(y[i]*sy) );
    }
//    for( i=0; i< np; i++)
//        g.fillOval( (int)(x[i]*sx)-2,(int)(y[i]*sy)-2,4,4);
  }

  public void paint( Graphics g)
  { return; }


} // end of class kohon