Octave MathNet与倍频程法方程计算的差异

这是我用c&MathNet计算法方程的代码：

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using MathNet.Numerics.LinearAlgebra;
using MathNet.Numerics.LinearRegression;
using MathNet.Numerics.LinearAlgebra.Double;

namespace ConsoleApplication1
{
    public class NormalEquation
    {
        public void Calc()
        {
            var xData = new double[4, 5]{{1, 2104, 5,1,45}, {1, 1416,3,2,40}, {1,1534,3,2,30},{1,852,2,1,36}};

            var yData = new double[4, 1] { { 460 }, { 232 }, { 315 }, { 178 } };

            Matrix<double> X = Matrix<double>.Build.DenseOfArray(xData);

            Matrix<double> Y = Matrix<double>.Build.DenseOfArray(yData);

            var beta = X.Transpose().Multiply(X).Inverse().Multiply(X.Transpose().Multiply(Y));

            foreach (double d in beta.Enumerate())
            {
                Console.WriteLine("{0}\t", d);
            }
        }
    }

    class Program
    {
        static void Main()
        {

            NormalEquation n = new NormalEquation();
            n.Calc();
        }
    }
}

有人能帮我理解为什么会这样吗-

MathNet结果是：beta={240,0.125,96，-56，-9}

倍频程结果是：β={188.40032,0.38663，-56.13825，-92.96725，-3.73782}

方阵X'*X几乎是奇异的。输入

X=[1 2104 5 1 45; 1 1416 3 2 40;1 1534 3 2 30; 1 852 2 1 36 ];
det(X'*X)

屈服

ans =   3.4192e-007

ans =   3.4192e-007