class BLAS {

    public static double dot(double[] x, double[] y) {
        Preconditions.checkArgument(x.length == y.length, "Array dimension mismatched.");
        double s = 0.;
        for (int i = 0; i < x.length; i++) {
            s += x[i] * y[i];
        }
        return s;
    }

}