// <APPLET CODE="SumSeries.class" WIDTH=413 HEIGHT=225></APPLET>
// Written by Nicholas D. Exner, Exner Enterprises C.2000, May 2000 
// Class DrawPoly uses code references to other classes such as
// ManagePanel.class and Box.class that are the intellectual propertyof
// Nicholas Exner.  These classes have been included here with the 
// consent of the author.

//N= 3620092 X: 15.679225524625934
import java.applet.*;
import java.awt.*;
import java.math.*;
import java.util.*;
import java.awt.event.*;
import java.awt.image.*; 

public class SumSeries extends Applet { // implements Runnable {
	boolean threadRun=true;
	Thread runner;
	Image offscreenImg;
	Graphics h;
	TextField tf,tft,tfcur;
	Choice digitIn;
	Image sumImg;

public void init(){
	sumImg = getImage(getCodeBase(),"title.gif");
	setLayout(new BorderLayout());
	setBackground(new Color(150,150,255));

	Panel p2 = new Panel();
	p2.setLayout(new FlowLayout(FlowLayout.LEFT));
	p2.setBackground(new Color(150,150,255));

	Panel p = new Panel();
	p.setLayout(new GridLayout(4,3,5,5));
	p.setBackground(new Color(150,150,255));
      offscreenImg = createImage(this.size().width, this.size().height);
      h = offscreenImg.getGraphics();
	tf = new TextField(6);
	tft = new TextField(6);
	tfcur = new TextField(6);

	tf.setText("0");
	tft.setText("0");
	tfcur.setText("0");

	digitIn    = new Choice();
	digitIn.addItem("Select Precision");
	for (int i=1;i<6;i++){
		digitIn.addItem(""+i);
	}
	digitIn.select("Select");
	p.add(new Label("Precision:"));
	p.add(digitIn);
	p.add(new Label("Current Term:"));
	p.add(tfcur);

	p.add(new Label("Partial Sum:"));
	p.add(tf);
	p.add(new Label("# of Terms:"));
	p.add(tft);

	p2.add(p);
	
	Panel hi = new Panel();
	hi.setLayout(new GridLayout(4,1));
	hi.add(new Button("Compute Next Term"));
	hi.add(new Button("Compute Next 10 Terms"));
	hi.add(new Button("Compute Next 100 Terms"));
	hi.add(new Button("Compute All"));
	p2.add(hi);
	add("South",p2);
}


public void paint(Graphics g){
	g.drawImage(sumImg,15,30,this);
}


public void calcSeries(){
	BigDecimal newx = new BigDecimal("1");
	BigDecimal oldx = new BigDecimal("0");
	BigDecimal change = new BigDecimal("1");
	int n=2;
	while(!oldx.equals(newx)){
		change = new BigDecimal(""+n);
		change = operationInverse(change,digitIn.getSelectedIndex());

		change = correctScale(change,digitIn.getSelectedIndex());
		newx = correctScale(newx,digitIn.getSelectedIndex());

		oldx = newx;

	//	System.out.print("C: "+change.toString());
	//	System.out.println(" D: "+newx.toString());

		newx = newx.add(change);
		newx = correctScale(newx,digitIn.getSelectedIndex());
		tf.setText(newx.toString());
		tft.setText(""+n);
		tfcur.setText(change.toString());
		n++;
	}
	if (digitIn.getSelectedIndex() < 1)
		tft.setText("0");
}

public void calcSeries(int xx){
	int n=(int)Integer.parseInt(tft.getText());
	int x = xx;
	if (n <= 0) {
		n=0;
		tft.setText("1");
		tf.setText("0");
		tfcur.setText("1");
		//x--;
	}

	BigDecimal newx = new BigDecimal(tf.getText());
	BigDecimal change = new BigDecimal(tfcur.getText());
	int nn = n+1;
	
	for (int i=nn;i<nn+x;i++) {
		change = new BigDecimal(""+i);
		change = operationInverse(change,digitIn.getSelectedIndex());

		change = correctScale(change,digitIn.getSelectedIndex());
		newx = correctScale(newx,digitIn.getSelectedIndex());

	//	System.out.print("C: "+change.toString());
	//	System.out.println(" D: "+newx.toString());

		newx = newx.add(change);
		newx = correctScale(newx,digitIn.getSelectedIndex());
		tf.setText(newx.toString());
		tft.setText(""+i);
		tfcur.setText(change.toString());
	}
	if (digitIn.getSelectedIndex() < 1)
		tft.setText("0");
}

public BigDecimal operationInverse(BigDecimal c,int ap){
	BigDecimal b = correctScale(new BigDecimal("1"),ap);
	BigDecimal d = correctScale(new BigDecimal("0"),ap);
	if (!c.equals(d))
		c = b.divide(c,ap+1,BigDecimal.ROUND_HALF_UP);

	c = correctScale(c,ap);
	return c;
}

public BigDecimal correctScale(BigDecimal b, int sc){
	boolean stillZero = true;
	int x = b.toString().indexOf('.');
	if (x < 0)
		x = b.toString().length();

	if (!b.equals(b.abs())) 
		sc++;

	b = b.movePointLeft(x);
		int ggg = slide(b);
		b = b.movePointRight(ggg);
	b = b.setScale(sc,BigDecimal.ROUND_HALF_UP);
		b = b.movePointLeft(ggg);
	b = b.movePointRight(x);

	return b;
}

public int slide(BigDecimal b){
	int slideRight = 0;
	boolean stillZero = true;
	for (int i=b.toString().indexOf('.')+1;i<b.toString().length();i++){
		if (b.toString().charAt(i)=='0' && stillZero)
			slideRight++;
		else
			stillZero = false;
	}	
	return slideRight;
}

public boolean action(Event evt, Object arg){
  if (arg.equals("Compute All")) {
	calcSeries();
  } else
  if (arg.equals("Compute Next 10 Terms")) {
	calcSeries(10);
  } else
  if (arg.equals("Compute Next 100 Terms")) {
	calcSeries(100);
  } else
  if (arg.equals("Compute Next Term")) {
	calcSeries(1);
  } else
  if (evt.target instanceof Choice) {
	System.out.println("Choice!");
	tf.setText("0");
	tft.setText("0");
	tfcur.setText("0");
  }
	return true;
}
} //END class