/* 
   Programmer: David A. Perry
   Course: CS 252
   Professor: Dr. Adams
   Date: October 17, 2004
   Assignment Name or Number: Homework 12
   Java Class Name: Progression
*/

/* 
   Input: Number 'n' of terms in a geometric progression, the initial term 'a'
          and the common ratio 'r'
   Output: Sum of the first 'n' terms using
           1) Iteration
           2) formula in book (excersise 23, section 2.2)
*/
import java.math.*;

public class Progression
{

   public static void main(String [] args)
   {
      double n, a, r, sum, temp;
      
      //initial term 'a'
        a = 2;
      //common ratio 'r'
        r = 3;
      //number of terms in progression
        n = 5;
      //initial sum
        sum = 0;
      //
        temp = 0;
      System.out.println("*****ITERATIVE*****");
      
      System.out.println(" ");
      System.out.println("Initial term is " + a);
      System.out.println("Common ratio is " + r);
      System.out.println("Number of terms in progression is " + n);
      
      for(int i = 0; i < n; i++)
      {
		   temp = a*Math.pow(r,i);
         sum = sum + temp;
      }
      //prints the total sum (if it were inside it would print it
      //every iteration
      System.out.println("Sum is " + sum);


      System.out.println(" ");
      System.out.println("*****FORMULA*****");
      System.out.println(" ");
      System.out.println("Formula is (a - (ar^n))/(1-r)");
      System.out.println(" ");
      
      //reinitialize variables
      a = 2;
      sum = 0;
      
      sum = (a - a*Math.pow(r,n))/(1 - r);
      System.out.println("Sum is " + sum);

      //end main
   }

   //end Progression
}