import java.applet.Applet;
import java.awt.*;
import java.awt.event.*;
import java.lang.Math;
public class function_plot extends Applet implements ActionListener{	
	// Applet for function-plotting. Stefan Emet 1998 
	TextField	TextField_parameter;
	Choice		Choice_function; 
	Button		Button_Draw; 
	int		activefunction=0,ITERATES=1;	
	final static int	COSINE=0,NONLINEAR=1,
				LOGISTIC=2,BAKER=3,TENT=4;
	double		MYY=2;

public void init(){	
	Choice_function = new Choice();      
	Choice_function.addItem("cos(x)");
	Choice_function.addItem(".5(x^3+x)");
	Choice_function.addItem("u x (1-x)");
	Choice_function.addItem("baker map");
	Choice_function.addItem("tent map");
	add(Choice_function);
	add(TextField_parameter=new TextField("",3));
	add(Button_Draw= new Button("Draw"));			
}
public void paint(Graphics g){
	// The width=400 and height=300 of
	// the Java Applet defined in funcplot.html
	Choice_function.move(0,0); // place the Choice resource in the nortwest corner of the Applet
	if (activefunction > 1){
		TextField_parameter.move(195,40);
		Button_Draw.move(250,40);
	}			
	TextField_parameter.show(activefunction > 1);
	Button_Draw.show(activefunction > 1);
	g.setColor(Color.white);
	g.fillRect(0,75,399,224);
	g.setColor(Color.black);
	g.drawRect(0,75,399,224);
	g.drawString("f(x) = ",150,17);
	switch (activefunction) {          
	case COSINE:	g.drawString("cos(x)",175,17);      
					plot_COSINE(g); break;
	case NONLINEAR:	g.drawString("0.5 (x^3+x)",175,17);	
					plot_NONLINEAR(g); break;
	case LOGISTIC:	g.drawString("u = ",170,54);		
					g.drawString("u x (1-x)",175,17);
					TextField_parameter.setText(""+MYY);
					plot_LOGISTIC(g); break;		
	case BAKER:		g.drawString("2x      , for  x in [0 , 0.5)",186,11);
					g.drawString("2x-1   , for  x in [0.5 , 1]",186,23);
					g.drawString("The n:th iterate:   f  (x) , n =",60,54);
					g.drawString("n",147,46);
					TextField_parameter.setText(""+ITERATES);
					plot_BAKER_TENT(g,ITERATES); break;
	case TENT:		g.drawString("2x      , for  x in [0 , 0.5)",186,11);
					g.drawString("2(1-x) , for  x in [0.5 , 1]",186,23);
					g.drawString("The n:th iterate:   f  (x) , n =",60,54);
					g.drawString("n",147,46);
					TextField_parameter.setText(""+ITERATES);
					plot_BAKER_TENT(g,ITERATES); break; 
	}
}
public void plot_COSINE(Graphics g){
	// plots the cosinus-function from -1 to PI in scalars
	// x=[-1,1], y=[-1,3.16]
	double x=-1,y;
	int xpix,ypix0,ypix1;
		y=Math.cos(x);				
		ypix0=187 - (int) (y*100);
		for (xpix=10;xpix<=390;xpix++){
			x=-1 + ((double)(xpix-9)/91);
			y=Math.cos(x);				
			ypix1=187 - (int) (y*100);
			g.drawLine(xpix,ypix0,xpix+1,ypix1);
			ypix0=ypix1;
		}
	g.drawLine(100,85,100,289);		// y-axis
	g.drawLine(10,187,390,187);		// x-axis
	g.drawLine(190,85,10,289);		// the line y=x
	g.drawString("f(x)=x",176,85);	// i.e. f(x)=x
	g.drawLine(167,189,167,185);	// x-tick at
	g.drawString("0.739",160,200);	// x=0.739 (x=cos(x))
}
public void plot_NONLINEAR(Graphics g){
	// plots the function: .5*(x^3+x)
	// x=[-1.2,1.2], y=[-2,2]
	double x=-1.2,y;
	int xpix,ypix0,ypix1;
		y=0.5*(Math.pow(x,3)+x);				
		ypix0=187 - (int) (y*55);
		for (xpix=10;xpix<=230;xpix++){
			x=-1.2 + ((double)(xpix-9)/92.5);						
			y=0.5*(Math.pow(x,3)+x);
			ypix1=187 - (int) (y*55);
			g.drawLine(xpix,ypix0,xpix+1,ypix1);
			ypix0=ypix1;
		}
	g.drawLine(120,80,120,290);		// y-axis
	g.drawLine(10,187,230,187);		// x-axis
	g.drawLine(10,253,230,121);		// the line y=x
	g.drawLine(118,105,122,105);	// y-tick at 
	g.drawString("1.5",100,110);	// y=1.5
	g.drawLine(118,269,122,269);	// y-tick at 
	g.drawString("-1.5",97,274);	// y=-1.5
	g.drawLine(28,185,28,189);		// x-tick at 
	g.drawString("-1",23,200);		// x=-1
	g.drawLine(214,185,214,189);	// x-tick at 
	g.drawString("1",212,200);		// x= 1
}
public void plot_LOGISTIC(Graphics g){
	// plots the logistic-function
	// pixels for x=[-0.3643,1.3], y=[-0.3643, ]
	double x=-0.3643,y;
	int xpix,ypix0,ypix1;
		y=MYY*x*(1-x);				
		ypix0=230 - (int) (y*140);
		for (xpix=10;xpix<=250;xpix++){
			x=-0.3643 + ((double)(xpix-9)/140);
			y=MYY*x*(1-x);				
			ypix1=230 - (int) (y*140);
			if (y >= -0.365 && y <= 1.1) {
				g.drawLine(xpix,ypix0,xpix+1,ypix1);
			}    
			ypix0=ypix1;
		}
	g.drawLine(60,85,60,289);	// y-axis
	g.drawLine(10,230,250,230);	// x-axis
	g.drawLine(10,280,200,90);	// the line y=x
	g.drawLine(58,91,200,91);	// the line y=1
	g.drawString("1",50,95);	// y=1
	g.drawLine(200,232,200,91);	// the line x=1
	g.drawString("1",197,247);	// x=1
}
public void plot_BAKER_TENT(Graphics g, int iterN){	
	int periods, x0, x1, half_interval;
	double interval;
	periods=(int)Math.pow(2,iterN);
	interval=(double)170/periods; half_interval=(int)interval/2;

	if (activefunction==BAKER){// plots the baker-map
		for (int i=1; i<=periods; i++) {
 			g.drawLine(60+(int)((i-1)*interval),260,60+(int)(i*interval),90);
		}		
	}
	else if	(activefunction==TENT){// plots the tent-map
		for (int i=1; i<=periods; i++) {
			x0=(int)((i-1)*interval)+60; x1=(int)(i*interval)+60;
			g.drawLine(x0,260,x0+half_interval,90);
 			g.drawLine(x0+half_interval,90,x1,260);
		}		
	}
	g.drawLine(60,85,60,280);	// y-axis
	g.drawLine(60,260,360,260);	// x-axis
	g.drawLine(60,260,230,90);	// the line y=x
	g.drawLine(58,90,62,90);	// y=1 tickmark
	g.drawString("1",50,95);	// y=1
	g.drawLine(230,258,230,262);// x=1 tickmark
	g.drawString("1",227,274);	// x=1
}
public void actionPerformed(ActionEvent e){
	Object source=e.getSource();
	if (source.equals(Choice_function)){
		activefunction=Choice_function.getSelectedIndex();	
	}			
	// Check if you have pressed the "Draw"-button:
	else if(source.equals(Button_Draw)){
		if (activefunction == LOGISTIC)
		 MYY=Double.valueOf(TextField_parameter.getText()).doubleValue();
		else 
		 ITERATES=Math.abs((int)Math.round(Double.valueOf(TextField_parameter.getText()).doubleValue()));
	}
	repaint();
}
}//  end of class function_plot