// twosource.java
// growth on renewable and nonrenewable sources
// adapted from a program in basic by H.T. Odum & E. Odum, 1994

import java.applet.Applet;
import java.awt.*;

public class twosource extends Applet{
  double j,n,q,k,k3,k4,k7,k8,jr,dq,dn,t,ti,qi,ni;
	Label pr1,pr2;
	TextField in1,in2;
  public void init(){
	  pr1 = new Label("Amount of nonrenewable resources N: ");
		in1 = new TextField("150",4);
		add(pr1);add(in1);
		pr2 = new Label("Amount of available renewable resources: ");
		in2 = new TextField("80",4);
		add(pr2);add(in2);
	}
	public boolean action (Event e, Object o){
	  n = (float)Integer.parseInt(in1.getText());
		j = (float)Integer.parseInt(in2.getText());
		repaint();
		return true;
	}
	public void paint (Graphics g){
	  q=1;k=0.1;k3=0.002;k4=0.0007;k7=0.0008;
		t=0;ti=0;qi=1;k8=0.03;ni=n;
		g.drawRect(60,80,320,180);
		while (t<320){
	  	jr=j/(1+k*q);
	  	dq=k7*n*q+k3*jr*q-k8*q;
	  	dn=-k4*n*q;
	  	q+=dq;
  		n+=dn;
  		t+=1;
  		g.setColor(Color.green);
  		g.drawLine((int)(60+ti),(int)(260-qi),(int)(60+t),(int)(260-q));
			g.setColor(Color.red);
			g.drawLine((int)(60+ti),(int)(260-ni),(int)(60+t),(int)(260-n));
			ti=t;qi=q;ni=n;
		}
	}
}
// Stefan Kontur & E. Ortega. September, 2000.