Calculating Pi

[SonniE]

this was an assignment i had todo today posting it here for no reason.
pretty much the program uses this weird algorithm.
http://mathworld.wolfram.com/GregorySeries.html
simply does pi = 4 * (1 - (1/3) + (1/5) - (1/7).......) etc
the more times you go through this pattern the more exact you get.



import java.util.Scanner;

public class PiCalc {

public static void main(String[] args) {
Scanner keyb = new Scanner(System.in);
double pi =0;
double numer = 1;
double denom = 1;
System.out.println("Enter the Number of iterations: ");
double counter = keyb.nextDouble();
while(counter>0)
{
pi+= numer/denom;
numer*=-1;
denom+=2;
counter--;
}
pi*=4.0;
System.out.println("Pi Was Calculated As: " + pi);
}
}


ran program with these parameters

Enter the Number of iterations:
799999999
Pi Was Calculated As: 3.1415926548383024

i googled pi and found it to be
3.141592653589793238462643383279502884197169399375 10582097494459230781640628620899862803482534211706 79.....