Chapter 5 Exercise 25, Introduction to Java Programming, Tenth Edition Y. Daniel LiangY.

**5.25 (Compute p) You can approximate p by using the following series:
$\pi =4\cdot (1-\frac{1}{3}+\frac{1}{5}+\frac{1}{7}-\frac{1}{9}+\frac{1}{11}-...+\frac{{(-1)}^{i+1}}{2i-1})$
Write a program that displays the p value for i = 10000, 20000, …, and 100000.

public class ProgrammingEx5_25 {
 public static void main(String[] args) {
 
  double pi = 0;
 
  for (int i = 1; i <= 100000; i++) {
   pi += Math.pow(-1, i + 1) / (2 * i - 1);
   if (i == 10000) {
    System.out.println("Pi at i = 10000 is " + pi*4);
   } else if (i == 20000) {
    System.out.println("Pi at i = 20000 is " + pi*4);
   } else if (i == 100000) {
    System.out.println("Pi at i = 100000 is " + pi*4);
   }
 
  }
   System.out.println("Java's pi is " + Math.PI);
 
 }
}