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class kalk3    // save as kalk3.java
  {
    public static void main (String [] args)
      {
        Grapher0 C = new Grapher0("yummypoos");
      }
  }

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import java.awt.*;                // save as Grapher0.java
import java.awt.event.*;
import java.io.*;

///////////////////////////////////////////////////////////////////////
//                   The Grapher0 class definition                   //
///////////////////////////////////////////////////////////////////////
public class Grapher0 extends Frame 
                             implements ActionListener, WindowListener
  {
    static final Color [] flavour = {Color.green, Color.blue, Color.red, 
                                     Color.black, Color.lightGray};

    class Display extends Canvas
     {
       public void paint(Graphics g)
         { 
           int w = getSize().width;  int h = getSize().height;
           g.drawRect(1, 1, w-2, h-2);
           g.setColor(Color.magenta);
           g.drawString(coffee, 30, 20);
           g.setFont(new Font("SansSerif", Font.PLAIN, 20));
         } 
       public Dimension getMinimumSize() {return new Dimension(50, 50);}
       public Dimension getPreferredSize() {return getMinimumSize();}       
     }

    class PlotCanvas extends Canvas
      { 
	public void paint(Graphics g)
          { 
            Dimension d = getSize();

	    g.setColor(flavour[3]);
	    g.drawRect(1, 1, d.width-2, d.height-2);
	    g.setColor(flavour[4]);
	    g.drawLine(1, d.height/2, d.width-2, d.height/2);
            g.setColor(flavour[1]);
	    //drawF(g, d.width-4, d.height-4);
            g.setColor(flavour[2]); 
            animateDrawF(g, d.width-4, d.height-4);  
	  }

       public Dimension getMinimumSize()   { return new Dimension(500, 300); }
       public Dimension getPreferredSize() { return getMinimumSize(); }    
      } // ------------- end of PlotCanvas class --------------------------


    private int f(double x, int ampltd)
      { return (int)( ampltd * x * x * Math.exp(-x)* Math.sin( x * 2 * Math.PI ) ); }

    private void drawF(Graphics g, int show_width, int show_height)
      { int freq = 8;
        int adjust = show_height/2;
        int ampltd = adjust;
        for (int x=0; x<show_width; x++)
          { 
            double xx  = (double) x * freq / show_width; 
            double xxx = (double) (x+1) * freq / show_width; 
            g.drawLine(x, -f(xx, ampltd) + adjust, x+1, -f(xxx, ampltd) + adjust);
          }
      }

    private void animateDrawF(Graphics g, int show_width, int show_height)
      { int freq = 8;
        int adjust = show_height/2;
        int ampltd = adjust;
        try{ for (int t=0; t<show_width; t++)
             { for (int x=0; x<t; x++)
               { 
               double xx  = (double) x * freq / show_width; 
               double xxx = (double) (x+1) * freq / show_width; 
               g.drawLine(x, -f(xx, ampltd) + adjust, x+1, -f(xxx, ampltd) + adjust);
               }
             }
             Thread.sleep(10);
           }
        catch(Exception e) { System.exit(0); }
      }

    private Display display  = new Display();
    private PlotCanvas display2 = new PlotCanvas();
    private Button [] nobs   = new Button[24];
    private String coffee    = "Nothing happened";
    final static String Sin="sin", Cos="cos", Tan="tan", Log="log", 
           Exp="exp", Pow="pow", Sqrt="sqrt";
    static String [] keys = {" 0 "," 1 "," 2 "," 3 "," 4 ",
                             " 5 "," 6 "," 7 "," 8 "," 9 ",
                             " . "," + "," - "," = "," * ",
                             " / "," % ","sin","cos","tan",
                             "log","exp","pow","sqrt"};
    final int digitStart = 0;
    final int posDot     = 10;
    final int opsStart   = 11;
    final int posEq      = 13;
    final int opsEnd     = 16;
    final int fonctStart = 17;
    final int fonctEnd   = 23;  

    private StringBuffer regA = new StringBuffer();
    private StringBuffer regB = new StringBuffer();
    private char operator;
    private String fonction;
    private boolean firstNoIn = false;
    private boolean doCalcNow = false;

    public Grapher0( String s )
      {
        super(s);
        display.setSize(30,100);
        setBackground(Color.yellow);
        addWindowListener(this);
        setLayout(new GridLayout(3,1));
        add(display);
        add(display2);
        Panel pad = new Panel();
        pad.setLayout(new GridLayout(8,3));
        for (int i=0; i<keys.length; i++)
          { nobs[i] = new Button(keys[i]);
            nobs[i].addActionListener(this);
            pad.add(nobs[i]);
          }
        add(pad);
        setSize(250,399);
        show();
      } // --------------- end of constructor

    // ---------- implementing WindowListener methods -----------
    public void windowClosed(WindowEvent evt){}
    public void windowDeiconified(WindowEvent evt){}
    public void windowIconified(WindowEvent evt){}
    public void windowActivated(WindowEvent evt){}
    public void windowDeactivated(WindowEvent evt){}
    public void windowOpened(WindowEvent evt){}
    public void windowClosing(WindowEvent evt){ System.exit(0); }

    public void actionPerformed(ActionEvent evt)
      {
        Object source = evt.getActionCommand();
        for (int i=digitStart; i<=posDot; i++)
          { if (source.equals(keys[i]))  //---- am I entering "numbers"?
              { if (firstNoIn)
                  { if (i != posDot ) regB.append(String.valueOf(i));
                    else              regB.append(".");
                    coffee = regB.toString(); display.repaint();
                    return;
                  }  // ends the "if" for the second number
                else
                  { if (i != posDot ) regA.append(String.valueOf(i));
                    else              regA.append(".");
                    coffee = regA.toString(); display.repaint();
                    return;
                  }  // ends the "else" for the first number
               }  //---- ends "if" for entering "numbers"
          }   //---- ends "loop" for checking "numbers"
        for (int j=opsStart; j<=opsEnd; j++)   //---- am I entering "operators"?
          { if ( source.equals(keys[j]) && j!=posEq ) //---- but not "="!!
              { operator = keys[j].charAt(1);
                firstNoIn = true;    // so must have finished the 1st no!!
                return;
              }
          }    //---- ends "loop" for checking "operators"

        for (int k=fonctStart; k<=fonctEnd; k++)
          { if ( source.equals(keys[k]) ) 
              { fonction = keys[k];
                if (fonction.equals("pow")) 
                  { firstNoIn = true; return; }
                doCalcNow = true;
                regB.append(0);
              }
           }

        if (source.equals(" = "))
           doCalcNow = true;

        if (doCalcNow)
          { coffee = doCalc(); display.repaint();
            //display.setText(doCalc());
            regA.setLength(0);
            regB.setLength(0);
            firstNoIn = false;
            doCalcNow = false;
            fonction = null;
            operator = ' ';
          }
      }  //------------ end of actionPerformed -------------------

    private String doCalc()
      {
        final char BEEP = '\u0007';
        try
          { // boolean notOp = false;
            double A = Double.parseDouble(regA.toString());
            double B = Double.parseDouble(regB.toString());
            switch (operator)
              { case '+': return String.valueOf(A + B);
                case '-': return String.valueOf(A - B); 
                case '*': return String.valueOf(A * B);
                case '/': return String.valueOf(A / B);
                case '%': return String.valueOf(A % B);
                // default : notOp = true;
               }
            // if ( notOp )
            if ( fonction.equals(Sin) ) return String.valueOf(Math.sin(A));
            if ( fonction.equals(Cos) ) return String.valueOf(Math.cos(A));
            if ( fonction.equals(Tan) ) return String.valueOf(Math.tan(A));
            if ( fonction.equals(Log) ) return String.valueOf(Math.log(A));
            if ( fonction.equals(Exp) ) return String.valueOf(Math.exp(A));
            if ( fonction.equals(Pow) ) return String.valueOf(Math.pow(A,B));
            if ( fonction.equals(Sqrt) ) return String.valueOf(Math.sqrt(A));
            else                        return "     ERROR";
          }
        catch (Exception ouch)
          { System.out.print(BEEP);
            return "     ERROR";
          }
      }  //---------- end of the doCalc() method ------------------
  } //---------------------- end of class Grapher0

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