Fix formatting and comments in correlation method

Author: kvadrik

src/main/java/com/thealgorithms/maths/Correlation.java

@@ -23,9 +23,9 @@ private Correlation() {
      */
     public static double correlation(double[] x, double[] y, int n) {
         double exy = 0; // E(XY)
-        double ex = 0;  // E(X)
+        double ex = 0; // E(X)
         double exx = 0; // E(X^2)
-        double ey = 0;  // E(Y)
+        double ey = 0; // E(Y)
         double eyy = 0; // E(Y^2)
         for (int i = 0; i < n; i++) {
             exy += x[i] * y[i];
@@ -39,10 +39,10 @@ public static double correlation(double[] x, double[] y, int n) {
         exx /= n;
         ey /= n;
         eyy /= n;
-        double cov = exy - ex * ey;             // Cov(X, Y) = E(XY)-E(X)E(Y)
+        double cov = exy - ex * ey; // Cov(X, Y) = E(XY)-E(X)E(Y)
         double varx = Math.sqrt(exx - ex * ex); // Var(X) = sqrt(E(X^2)-E(X)^2)
         double vary = Math.sqrt(eyy - ey * ey); // Var(Y) = sqrt(E(Y^2)-E(Y)^2)
-        if (varx * vary < DELTA) { //Var(X) = 0 means X = const, the same about Y
+        if (varx * vary < DELTA) { // Var(X) = 0 means X = const, the same about Y
             return 0;
         } else {
             return cov / Math.sqrt(varx * vary);