import java.applet.*;
import java.awt.*;
import java.awt.event.*;

public class Applet1 extends Applet implements Runnable
{
    int versuche;
    int vert;
    int breite;
    int max;
    int a;
    int b;
    int e;
    int r;
    int outOfBound;
    int temp;
    int yVersatz;
    int xVersatz;
    Thread verteilung;
    
    public int gleichvert(double a, double b) 
    {
        double temp=0;
        temp=(b-a)*Math.random()+a;
        return Math.round((float)temp);
    }
    
    //Exponentialverteilte WDF: Achtung Intervalle nur bis 3faches des  Erwartungswertes
    public int expvert(double a) 
    {
        double temp=0;
        temp=-a*Math.log(1-Math.random());
        return Math.round((float)temp);
    }
    
    //Erlangverteilte WDF: Achtung Intervalle nur bis 3faches des Erwartungswertes
    public int erlvert(double a, double b) 
    {
        int i=0;
        double temp=0;
        while (i<b) 
        {
            temp+=-a*Math.log(1-Math.random());
            i++;
        }
        return Math.round((float)(temp/b));
    }
    
    //Rampenverteilte WDF
    public int rampenvert(double a, double b) 
    {
        double temp=0;
        temp=(b-a)*Math.sqrt((Math.random()/2))+a;
        return Math.round((float)temp);
    }
    
    //Dreiechverteilte WDF
    public int dreieckvert(double a, double b) 
    {
        double temp=Math.random();
        double temp2=0;
        if (temp<0.5) 
        {
            temp2=(a+(b-a)*Math.sqrt(temp/2) );
        } 
        else 
        {
            temp2=(b-(b-a)*Math.sqrt((1-temp)/2));
        }
        return Math.round((float)temp2);
    }
    
    public void start()
    {
        if (verteilung==null)
        {
            repaint();
            verteilung=new Thread(this);
            verteilung.start();
        }
    }
    
    public void stop()
    {
        if (verteilung!=null)
        {
            verteilung.stop();
            verteilung=null;
        }
    }
    
    public void init()
    {
        breite =getSize().width-10;
        versuche=100*getSize().width;
        max=0;
        a=20;
        b=breite-20;
        e=breite/4;
        r=5;
        outOfBound=0;
        yVersatz=getSize().height;
        xVersatz=10;
        List l =new List(2,false);
        l.addItem("Gleich");
        l.addItem("Expotential");
        l.addItem("Erlang");
        l.addItem("Rampre");
        l.addItem("Dreieck");
        
        l.addActionListener (new ActionListener()
        {
            public void actionPerformed(ActionEvent e)
            {
                if (e.getActionCommand().equals("Gleich")) 
                {
                    vert = 1;
                }
                else if (e.getActionCommand().equals("Expotential")) 
                {
                    vert = 2;
                }
                else if (e.getActionCommand().equals("Erlang")) 
                {
                    vert = 3;
                }
                else if (e.getActionCommand().equals("Rampre")) 
                {
                    vert = 4;
                }
                else if (e.getActionCommand().equals("Dreieck")) 
                {
                    vert = 5;
                }
                stop();
                start();
            }
        });
        
        add(l);
    }
    
    public void run()
    {
        try 
        {
            for (;;)
            {
                int histo[] = new int[breite];
                Graphics g = getGraphics();
                for (int i=0;i<versuche;i++) 
                {
                    temp=0;
                    switch(vert)
                    {
                        case 1:
                        {
                            temp=gleichvert(a,b);
                            break;
                        }
                        case 2:
                        {
                            temp=expvert(e);
                            break;
                        }
                        case 3:
                        {
                            temp=erlvert(e,r);
                            break;
                        }
                        case 4:
                        {
                            temp=rampenvert(a,b);
                            break;
                        }
                        case 5:
                        {
                            temp=dreieckvert(a,b);
                            break;
                        }
                    }
                    if (temp>=breite | temp<0) outOfBound++;
                    else histo[temp]++;
                }
                max=0;
                for (int i=0;i<breite;i++)
                {
                    if (max<histo[i]) 
                    {
                        max=histo[i];
                    }
                }
                g.setColor(getBackground());
                g.fillRect(0,0,getSize().width,getSize().height);
                g.setColor(Color.black);
                int i=0;
                for (int x=xVersatz;x<breite+xVersatz;x++)
                {
                    int y =yVersatz-histo[i++]*(yVersatz-50)/max;
                    g.drawLine(x,yVersatz,x,y);
                }
                verteilung.sleep(50);
            }
        } 
        catch (InterruptedException ex) 
        {
            System.out.println(ex);
        }
    }
}