code: public static double dot(DoubleMatrix x, DoubleMatrix y) {
  		//return NativeBlas.ddot(x.length, x.data, 0, 1, y.data, 0, 1);
  		return JavaBlas.rdot(x.length, x.data, 0, 1, y.data, 0, 1);
  	}
docs: Compute x^T * y (dot product)