// develop.java
// economic development of a nation
// adapted from a program in basic by H.T. Odum & E. Odum, 1994.

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

public class develop extends Applet
{

 Label prompt1,prompt2,prompt3;
 TextField input1,input2,input3;
 double p1,p2,p3;
 int t;
 double k0,k1,k2,k3,k4,k5,k6,k7,k8,k9;
 double n1,n2,n3,n4,n5,n6,n7,n8;
 double i0,t0,n0,a0,m0,d0,f0;
 double dt,dd,df,dn,da,dm;
 double ne,iv,ir,a,n,m,d,f,r;
 Button drawbutton;

 public void init()
 {
	prompt1 = new Label("P1 Prices of goods and services: ");
	input1 = new TextField("250",4);
	add(prompt1);add(input1);

	prompt2 = new Label("P2 Price for finished products: ");
	input2 = new TextField("100",4);
	add(prompt2);add(input2);

	prompt3 = new Label("P3 Price for raw products: ");
	input3 = new TextField("50",4);
	add(prompt3);add(input3);

	drawbutton = new Button("Draw"); add(drawbutton);
 }

 public boolean action(Event e, Object o)
 {
	p1=(float)Integer.parseInt(input1.getText());
	p2=(float)Integer.parseInt(input2.getText());
	p3=(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);

		k0=2.3; k1=3; k2=0.033; k3=0.1; k4=0.02; k5=0.01; k6=3; k7=0.02; k8=0.01; k9=0.0067;
		n1=0.0067; n2=0.033; n3=0.1; n4=0.067; n5=0.01; n6=0.0022; n7=0.001; n8=0.01;
		i0=1; t0=1;n0=0.05; a0=0.015; m0=0.05; d0=2; f0=0.08;
		dt=0.5; t=0; p2=0; p3=0;
		ne=3; iv=0.1; ir=0.1; a=0.1; n=0.3; m=0.1; d=0.5; f=10;

	do
	{
	 g.setColor(Color.blue);
	 g.drawOval(t,(int)(300-f/f0),1,1);

	 g.setColor(Color.green);
	 g.drawOval(t,(int)(300-a/a0),1,1);

	 g.setColor(Color.magenta);
	 g.drawOval(t,(int)(300-n/n0),1,1);

	 g.setColor(Color.red);
	 if (190-m/m0>90) g.drawOval(t,(int)(190-m/m0),1,1);
	 else
	 g.drawOval(t,190,1,1);

	 g.setColor(Color.yellow);
	 if (190-d/d0>90) g.drawOval(t,(int)(190-d/d0),1,1);
	 else
	 g.drawOval(t,190,1,1);

	r=i0/(1+k0*n*a+k1);
	p3=p3+1*dt;
	dd=iv-n5*d*m;
	df=-n8*f*a;
	dn=k7*a*n-k8*n-k9*n+n1*a*ne-n2*r*a*n-n6*n*n;
	da=k2*r*a*n+k3*r-k4*a-k5*a*n+k6*m/p3+n7*f*a;
	dm=p1*n3*r+p2*n4*r*a*n-k6*m+iv-n5*d*m-ir*d;
	a=a+da*dt;
	if (a<0.001) a=0.001;
	  n=n+dn*dt;
	  m=m+dm*dt;
	if (m<0.0001) m=0.0001;
	  d=d+dd*dt;
	  f=f+d*dt;
	if (f<0) f=0;
	  t=t+1;
 	}while (t<320);
 }
}
// Camila Duarte & E. Ortega, January 30th, 2001