public static void MNIST2()
        {
            DataSet dataSet = new DataSet("mnist2.txt", ' ', 10, false);
            var     p       = new Perceptron(600, 3, ErrorFunction.CrossEntropy()).Layer(784, null).Layer(16, ActivationFunction.Sigmoid())
                              .Layer(16, ActivationFunction.Sigmoid()).Layer(10, ActivationFunction.Sigmoid());

            p.Train2(dataSet, 200);
            double mse = p.CalculateMeanErrorOverDataSet(dataSet);
        }