8b

Advanced Placement

Computer Science Lab

 

 

Recursion and Iteration

 

 

 

 

Introduction

 

This is another exercise to provide an example of the use of recursion.  Use the following time algorithm to compare a recursive method with an iterative method.

 

 

 

 

 

long time;

time = System.currentTimeMillis();

System.out.print(“System time is milliseconds “);

System.out.println(time);

 

 

 

 

 

Programming Assignment

 

Write two programs.   Each will calculate the constant e or Euler’s constant which is given as:

 

e = 1 + 1/1! + 1/2! + 1/3!  +…+ 1/n!

 

Write the programs to run the calculation to ten decimal places.  One program will use an iterative method to do the calculation and one program will use a recursive method to do the calculation.  Compare the times of the two algorithms.  Why do you suppose that they are so different?