package com.itranswarp.learnjava;

/**

* for练习

*/

public class Main {

public static void main(String[] args) {

double pi = 0;

int flag=-1;

for (int i = 1; i < 100000; i += 2) {

// TODO:

flag*=-1;

pi+=(flag)*1.0/i;

}

System.out.println(pi*4);

}

}