public class Practice3 {
//求pi/4=1-1/3+1/5-1/7...
public static double calcPi(int n) {
double Pi=0;
for(int i=0 ;i<n;i++) {
int m=2*i+1;
if (i%2==0) {
Pi=Pi+1.0/m;
}
else {
Pi=Pi-1.0/m;
}
}
return Pi*4;
}
public static void main (String[] args) {
double b;
b=calcPi(6000);
System.out.println(b);
}
}
