A = [12.1 6.6 11.5 8.7 15.4 6.9 8.8 10.1 19.1 15.6 22.2 10.2 15.7 10.0 7.2 11.8 11.3 12.5 11.4 12.9
          6.9 7.5  6.1 8.1  9.0 6.0 8.5  8.3 11.2  7.6  9.3  7.5  9.2 6.4  6.3  7.7  8.3  7.5  9.5  9.3];

    B = A - mean(A, 2);

    C = cov(B');
    [V, ~] = eig(C);
    plotv(V);