// intecon.java
// nation with international money circulation
// adapted from a program in basic by H.T. Odum & E. Odum, 1994

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

public class intecon extends Applet
{

 Label prompt1,prompt2,prompt3;
 TextField input1,input2,input3;
 double tm,it,d;
 int t;
 double q,f,m,i,id,x,s,p,pq,c,y,l;
 double d0,p0,q0,f0,t0;
 double dt,df,dq,dm,dd,did,gnp;
 double p1,p2,p3;
 double k0,k1,k2,k3,k4,k5,k6,k7,k8,k9,k10,k11,k12,k13,k14,k15,k16,k17,k18;
 Button drawbutton;

 public void init()
 {
	prompt1 = new Label("IT Interest rate: ");
	input1 = new TextField("3",4);
	add(prompt1);add(input1);

	prompt2 = new Label("TM Home country's money supply: ");
	input2 = new TextField("15",4);
	add(prompt2);add(input2);

	prompt3 = new Label("D Debt: ");
	input3 = new TextField("0",4);
	add(prompt3);add(input3);

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

 public boolean action(Event e, Object o)
 {
	it=0.01*(float)Integer.parseInt(input1.getText());
	tm=0.1*(float)Integer.parseInt(input2.getText());
	d=(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);

	t=0; q=158; f=211; m=0.5; i=1; id=0; x=1; l=1;
	d0=5; p0=5; q0=0.5; f0=0.4; t0=5;
	dt=0.1; p=0; y=0;
	p1=1; p2=1; p3=0.001;
	k0=3; k1=0.0014; k2=0.063; k3=10; k4=0.00054; k5=0.0000000093; k6=0.063;
	k7=10; k8=0.02; k9=0.05; k10=0.3; k11=0.018000001; k12=0.5; k13=3.7;
	k14=0.05; k15=0.6; k16=1; k17=2; k18=1.2;
	do
	{
	 g.drawRect(0,90,320,210);
	 g.drawLine(0,190,320,190);

	 g.setColor(Color.blue);
	 g.drawOval(t,(int)(300-q*q0),1,1);

	 g.setColor(Color.green);
	 g.drawOval(t,(int)(300-p*p0),1,1);

	 g.setColor(Color.red);
	 g.drawOval(t,(int)(190-f*f0),1,1);

	 g.setColor(Color.orange);
	 g.drawOval(t,(int)(190-d*d0),1,1);

	 s=i/(1+k5*(f+k9*m/p3)*q+k6*q+k7);
	 df=-k4*s*q*(f+k9*m/p3);
	 p=k1*s*q*(f+k9*m/p3)+k2*s*q+k3*s-y*k12*l/p1;
	 if (p<0) p=0;
	  else y=1;
	 pq=p+k10*m/p2;
	 dq=p-k8*q+k10*m/p2;
	 dm=k13*l*it+y*k12*l-k9*m-k10*m-it*d-k16*m-k14*m+k17*id*l+k18*it*id;
	 dd=k13*l*it-x*k11*d*m;
	 did=k16*m-k17*id*l;
	 gnp=k0*m+k9*m+k10*m+k14*m+x*k11*d*m+d*it+k16*m;
	 f=f+df*dt;
	 if (f<0) f=0;
	 q=q+dq*dt;
	 if (q<1) q=1;
	 m=m+dm*dt;
	 if (m<0.1) m=0.1;
	 d=d+dd*dt;
	 if (d<0) d=0;
	 id=id+did*dt;
	 if (id<0) id=0;
	 l=tm-m;
	 if (l<0) l=0;
	 t=t+1;
	 c=pq/gnp;
	 p1=1/c;
	 g.setColor(Color.black);
	 g.drawLine(0,190,320,190);
	}while (t<320);
 }
}

// Camila Duarte & E. Ortega. January 31th, 2001