Calculate Auto And Cross-correlation From A File

I have to calculate auto and cross-correlation from a file, like this:

Rxx(n)= 1/N* SUM[from k=1 to N-n]((x(k)-x(mean))*x(k+n)-x(mean))

and after

Rxy(n)= 1/N* SUM[from k=1 to N-n]((x(k)-x(mean))*y(k+n)-y(mean))

I've 600 x an y,

k = the numbers of x (N is the last one)
n = 0....N-1

already calculated mean, and I've tried the following (but it doesnt work):

String sor;
int i=0;
while ((sor = br.readLine()) != null) {
String [] adatok =sor.trim().split(",");

[Code] ....