// econpac.java
// Production, Prices and Consumption
// adapted from a program in basic by H.T. Odum & E. Odum, 1994

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

public class econpac extends Applet
{

 Label prompt1,prompt2,prompt3;
 TextField input1,input2,input3;
 double tm,p1,m1;
 Button drawbutton;

 public void init()
 {
	prompt1 = new Label("TM Total money supply: ");
	input1 = new TextField("100",4); add(prompt1);add(input1);
	prompt2 = new Label("P1 Price of products: ");
	input2 = new TextField("1",4);	 add(prompt2);add(input2);
	prompt3 = new Label("M1 Producers money ");
	input3 = new TextField("30",4);	 add(prompt3);add(input3);
	drawbutton = new Button("Draw"); add(drawbutton);
 }

 public boolean action(Event e, Object o)
 {
	tm=(float)Integer.parseInt(input1.getText());
	p1=(float)Integer.parseInt(input2.getText());
	m1=(float)Integer.parseInt(input3.getText());
	repaint();
	return true;
 }

 public void paint(Graphics g)
 {
	g.drawRect(0,90,320,210);
	g.drawLine(0,190,320,190);
	int t;
	double i,c,q,r,p,jg,js;
    double p2,m2;
    double q0,m0,c0,t0;
    double dq,dm,dc,dt;
    double k0,k1,k2,k3,k4,k5,k6;
	t=1;
	i=1;c=10;q=10;r=0;p=0;jg=0;js=0;
	p2=2.5;m2=0;
	q0=0.5;m0=1;c0=0.1;t0=0.3;
	dq=0;dm=0;dc=0;dt=2;
	k0=45; k1=0.01; k2=0.01; k3=0.0003; k4=50; k5=0.005; k6=1.0;

	do
	{
	 g.setColor(Color.blue);
	 if (300-q>90)	 g.drawOval(t,(int)(300-q*q0),1,1);	else g.drawOval(t,90,1,1);
	 g.setColor(Color.green);
	 if (300-c>90) g.drawOval(t,(int)(300-c*c0),1,1);   else g.drawOval(t,90,1,1);
	 g.setColor(Color.red);
	 if (190-m1>90) g.drawOval(t,(int)(190-m1*m0),1,1); else g.drawOval(t,190,1,1);
	 g.setColor(Color.pink);
	 if (190-m2>90) g.drawOval(t,(int)(190-m2/m0),1,1); else g.drawOval(t,190,1,1);

	 r=i/(1+k0*jg);
	 p=k4*r*jg;
	 jg=k2*m1/p2;
	 js=k1*m2/p1;
	 dq=p-k5*q-js;
	 dm=k1*m2-k2*m1;
	 dc=k6*js-k3*c-jg;
	 q=q+dq*dt;
	 if (q<0) q=0;
	 c=c+dc*dt;
	 if (c<0) c=0;
     m1=m1+dm*dt;
     m2=tm-m1;
	 t=t+1;
	}
	while (t<320);
	g.drawLine(0,190,320,190);
 }
}
// Camila Duarte & e. Ortega, January 24th, 2001