#vulnerable code 
                                @Override
    public float getCovariance(float scale) {
        assert (num_updates > 0) : num_updates;
        return (sum_inv_covar * scale) * num_updates; // Harmonic mean
    } 
                            #location 4 
                            #vulnerability type UNSAFE_GUARDED_BY_ACCESS
#fixed code
                                @Override
    public float getCovariance(float scale) {
        return 1.f / (sum_inv_covar * scale);
    }