public class Newton_Applet5 extends java.applet.Applet
{
 // Put property data between these lines
 //------------------------------------------------
 // Data for a ballistic trajectory at a given angle
 double tan = Math.tan(Math.PI / 4.0);
 double cos = Math.cos(Math.PI / 4.0);
 double g = 9.8; // m/s^2
 double v0 = 100; // m/s
 //------------------------------------------------

 public void init()
 {   
   // Put code between this line
   //--------------------------------------------------

     double double xl = 0.0;
     double xh = 1.0;
     double step = 1.0;
     double dif = 1.0;

     // Constants
     double maxSteps = 50000;
     double tol = 1.0E-2;

     int numSteps = 0;
     int numStepsNewton = 0;

     // First look for the "turn over" of the parabola
     while (f_method(xl) * f_method(xh) < 0 )
     {
         xl += step;
         xh += step;
         numSteps++;
         // Give up if gone too far
         if( numSteps > maxSteps)
         {
           System.out.println("No turn over found");
           return;
         }
     }

     // Now that we are on the "down" side,
     // use Newton's method to find the intercept.
     xl = xh;
     do
     {
       double deriv = fp_method(xl);
       if( deriv == 0.0)
       {
         System.out.println("Derivative = 0.0");
         return;
       }
       xh = xl - (f_method(xl)/deriv);// Newton formula
       dif = Math.abs(xh-xl);
       xl = xh;
       numStepsNewton++;
     } while ( dif > tol && numStepsNewton < maxSteps);

     System.out.println("After steps ="+numSteps);
     System.out.println(" & Newton steps = "+numStepsNewton);
     System.out.println("Root x = "+xm+
                        " within tolerance ="+dif);
    //--------------------------------------------------
    // and this line.
  }

  double f_method(double x)
  {
   // Put code between this line
   //--------------------------------------------------
     double val = x*tan - (0.5*g*x*x)/(v0*v0*cos*cos); ;
     return val;
   //--------------------------------------------------
   // and this line.
  }

  double fp_method(double x)
  {
   // Put code between this line
   //--------------------------------------------------
     double val = tan - (g*x)/(v0*v0*cos*cos); ;
     return val;
   //--------------------------------------------------
   // and this line.
  }

  // Paint message in Applet window.
  public void paint(java.awt.Graphics g)
  { g.drawString("Newton_Applet5",20,20); }

  // Can also run this program as an application.
  // No windowing needed so just run the applets
  // init() function.
  public static void main(String [] args)
  {
    Newton_Applet5 obj = new Newton_Applet5();
    obj.init();
  }
}