/*************************************************************************
 *  Compilation:  javac PointPolar.java
 *  Execution:    java PointPolar
 *
 *  Implementation of 2D point using polar coordinates.
 *
 *************************************************************************/

class PointPolar {
   private double r, theta; 
   
   PointPolar() {
      double x = Math.random();
      double y = Math.random();
      r = Math.sqrt(x*x + y*y); 
      theta = Math.atan2(y, x);
   }

   PointPolar(double x, double y) {
      r = Math.sqrt(x*x + y*y); 
      theta = Math.atan2(y, x);
   }

   double r()     { return r;                 }
   double theta() { return theta;             }
   double x()     { return r*Math.cos(theta); }
   double y()     { return r*Math.sin(theta); }

   double dist(PointPolar p) {
      double dx = x() - p.x();
      double dy = y() - p.y();
      return Math.sqrt(dx*dx + dy*dy);
   }

   public String toString()  { return "(" + x() + ", " + y() + ")"; } 



   // test client
   public static void main(String[] args) {
      PointPolar p = new PointPolar();
      System.out.println("p  = " + p);
      System.out.println("   x     = " + p.x());
      System.out.println("   y     = " + p.y());
      System.out.println("   r     = " + p.r());
      System.out.println("   theta = " + p.theta());
      System.out.println();

      PointPolar q = new PointPolar(0.5, 0.5);
      System.out.println("q  = " + q);
      System.out.println("dist(p, q) = " + p.dist(q) + " = " + q.dist(p));
   }
}