Karl Pearson's Correlation Coefficient

/**
 * Program to calculate Karl Pearson's correlation coefficient.
 */
import java.util.*;
public class KPearson_Correlation
{
    static int[] calculateXY(int[] x, int[] y) //Method to get XY.
    {
        int num = x.length;
        int i, prod;
        int[] xy = new int[num];
        for(i=0;i<num;i++)
        {
            prod = x[i]*y[i];
            xy[i] = prod;
            prod = 0;
        }

        return xy;
    }

    static int[] calculateX2(int[] x) //Method to get X2.
    {
        int num = x.length;
        int i, xsquare;
        int[] x2 = new int[num];
        for(i=0;i<num;i++)
        {
            xsquare = x[i]*x[i];
            x2[i] = xsquare;
            xsquare = 0;
        }

        return x2;
    }

    static int[] calculateY2(int[] y) //Method to get Y2.
    {
        int num = y.length;
        int i, ysquare;
        int[] y2 = new int[num];
        for(i=0;i<num;i++)
        {
            ysquare = y[i]*y[i];
            y2[i] = ysquare;
            ysquare = 0;
        }

        return y2;
    }

    static long getSum(int[] num) //Method to get the sum of any list.
    {
        int sum = 0;
        int i;
        for(i=0;i<num.length;i++)
        {
            sum += num[i];
        }

        return sum;
    }


    static void display(int[] x, int[] y ,int[] xy, int[] x2, int[] y2) //Method to neatly display all the lists along with their sums.
    {
        System.out.println();
        System.out.println("X\tY\tXY\tX^2\tY^2"); //Displaying the headings.

        int num = x.length;
        int i;
        for(i=0;i<num;i++)
        {
            System.out.println(x[i]+"\t"+y[i]+"\t"+xy[i]+"\t"+x2[i]+"\t"+y2[i]); //Displaying the values.
        }

        System.out.println("---\t---\t---\t---\t---");
        System.out.println(getSum(x)+"\t"+getSum(y)+"\t"+getSum(xy)+"\t"+getSum(x2)+"\t"+getSum(y2)); //Displaying the sums.
        System.out.println("---\t---\t---\t---\t---");

    }

    static double getAnswer(int[] x, int[] y ,int[] xy, int[] x2, int[] y2) //Method to get the correlation coefficient [r].
    {
        long xsum, ysum, xysum, x2sum, y2sum;
        int num = x.length;
        xsum = getSum(x);
        ysum = getSum(y);
        xysum = getSum(xy);
        x2sum = getSum(x2);
        y2sum = getSum(y2);

        double r;
        r = ( xysum - ((xsum*ysum)/num) ) / ( Math.sqrt(x2sum - ((xsum * xsum) / num)) * Math.sqrt(y2sum - ((ysum * ysum) / num)) );

        return r;
    }

    public static void main(String[] args)
    {
        //Getting the user's input.
        Scanner sc = new Scanner(System.in);
        System.out.println("Please enter the number of items to be placed in both columns.");
        int num = sc.nextInt();
        int[] x = new int[num];
        int[] y = new int[num];
        System.out.println("Please enter the values in the first column. [X]");
        int i;
        for(i=0;i<x.length;i++)
        {
            x[i] = sc.nextInt();
        }
        System.out.println("Please enter the values in the second column. [Y]");
        for(i=0;i<x.length;i++)
        {
            y[i] = sc.nextInt();
        }

        //Getting the other lists required.
        int[] xy = calculateXY(x,y);
        int[] x2 = calculateX2(x);
        int[] y2 = calculateY2(y);

        //Displaying everything.
        display(x,y,xy,x2,y2);

        //Calculating the correlation coefficient [r].
        double r = getAnswer(x,y,xy,x2,y2);
        System.out.println("Correlation = "+r);

        sc.close();

    }
}