/// <summary>/// 遞歸計算行列式的值/// </summary>/// <param name="matrix">矩陣</param>/// <returns></returns>public static double Determinant(double[][] matrix){  //二階及以下行列式直接計算  if (matrix.Length == 0) return 0;  else if (matrix.Length == 1) return matrix[0][0];  else if (matrix.Length == 2)  {    return matrix[0][0] * matrix[1][1] - matrix[0][1] * matrix[1][0];  }  //對第一行使用“加邊法”遞歸計算行列式的值  double dSum = 0, dSign = 1;  for (int i = 0; i < matrix.Length; i++)  {    double[][] matrixTemp = new double[matrix.Length - 1][];    for (int count = 0; count < matrix.Length - 1; count++)    {      matrixTemp[count] = new double[matrix.Length - 1];    }    for (int j = 0; j < matrixTemp.Length; j++)    {      for (int k = 0; k < matrixTemp.Length; k++)      {        matrixTemp[j][k] = matrix[j + 1][k >= i ? k + 1 : k];      }    }    dSum += (matrix[0][i] * dSign * Determinant(matrixTemp));    dSign = dSign * -1;  }  return dSum;}

static void Main(string[] args){  //二階行列式 -2  double[][] matrix1 = new double[][]  {    new double[] { 1, 2 },    new double[] { 3, 4 }  };  Console.WriteLine(Determinant(matrix1));  //三階行列式 -4  double[][] matrix2 = new double[][]  {    new double[] { 2, 0, 1 },    new double[] { 1, -4, -1 },    new double[] { -1, 8, 3 }  };  Console.WriteLine(Determinant(matrix2));  //四階行列式 -21  double[][] matrix3 = new double[][]  {    new double[] { 1, 2, 0, 1 },    new double[] { 1, 3, 5, 0 },    new double[] { 0, 1, 5, 6 },    new double[] { 1, 2, 3, 4 }  };  Console.WriteLine(Determinant(matrix3));  Console.ReadLine();}