import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.lang.Math.*;
import java.math.BigInteger;
import java.math.BigDecimal;

public class BigDecEx extends JApplet implements ActionListener{

   JLabel lN1, lN2, lP;
   JTextField tN1, tN2, tP;
   JButton btnAdd,btnSub,btnMul,btnDiv,btnSqrt,btnClear; JTextArea outArea;
   public void init(){
      Box box=Box.createVerticalBox();
      // input
      lN1=new JLabel("Input first number"); box.add(lN1);
      tN1=new JTextField(100); tN1.setEditable(true); box.add(tN1);

      lN2=new JLabel("Input second number"); box.add(lN2);
      tN2=new JTextField(100); tN2.setEditable(true); box.add(tN2);

      lP=new JLabel("Precision of results"); box.add(lP);
      tP=new JTextField(20); tP.setText("200");
      tP.setEditable(true); box.add(tP);

      // buttons
      btnAdd=new JButton("+"); btnAdd.addActionListener(this); box.add(btnAdd);
      btnSub=new JButton("-"); btnSub.addActionListener(this); box.add(btnSub);
      btnMul=new JButton("*"); btnMul.addActionListener(this); box.add(btnMul);
      btnDiv=new JButton("/"); btnDiv.addActionListener(this); box.add(btnDiv);
      btnSqrt=new JButton("sqrt"); btnSqrt.addActionListener(this); box.add(btnSqrt);
      btnClear=new JButton("Clear"); btnClear.addActionListener(this); box.add(btnClear);

      // Output
      String desc="This is a rudimentary arbitrary precision decimal calculator\n";
      outArea=new JTextArea(desc,30,60);
      ScrollPane scrollPane=new ScrollPane();
      scrollPane.add(outArea);
      box.add(scrollPane);

      Container c=getContentPane();
      c.add(box);
      setSize(600,300);
      setVisible(true);
      showStatus("Enter operands and operator");
  }

  public BigDecimal bSqrt(BigDecimal N, int nP){
    // Example: sqrt(2) to 20,000 decimal places required 11 iterations in 68 seconds.
    if(N.signum()<=0)return BigDecimal.ZERO;  // return zero for neg. arguments
    double x=java.lang.Math.sqrt(N.doubleValue());
    BigDecimal X1=new BigDecimal(x); // Initial approximation
    BigDecimal X=BigDecimal.ZERO;
    int count=0, maxCount=0,nP1=nP;
    // maxCount is max. number of iterations, where 16*2^maxCount>=nP
    for(maxCount=0;maxCount<1000;maxCount++){nP1/=2;if(nP1==0)break;}
    BigDecimal residue=BigDecimal.ONE;
    while(residue.compareTo(BigDecimal.ZERO)!=0 && count