行列式计算（C#）

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Text;
 5 
 6 namespace Nrow_culmn
 7 {
 8     class Program
 9     {
10         public static double jlength = 0;
11         static void Main(string[] args)
12         {
13             //double[,] row_culmn = { { 3, 1, -1, 1 }, { 1, -1, 1, 2 }, { 2, 1, 2, -1 }, { 1, 0, 2, 1, } };
14             //行列式二维数组
15             double[,] row_culmn = { { 1, 4, 9, 16 }, { 4, 9, 16, 25 }, { 9, 16, 25, 36 }, { 16, 25, 36, 49} };
16             
17             
18             
19             for (int i = 0; i < 4; i++)
20             {
21                 for (int j = 0; j < 4; j++)
22                 {
23                     Console.Write(row_culmn[i, j].ToString() + "  ");
24                 }
25                 Console.WriteLine();
26             }
27             Console.WriteLine();
28             Console.WriteLine();
29             Console.WriteLine();
30             int row = 0;//行
31 
32             int rowup = 1;//向右移动的偏移列（相对行）
33             jlength = Math.Sqrt(row_culmn.Length);
34 
35             for (row = 0; row < jlength - 1; row++)
36             {
37                 //递归算法将行列式计算为做下三角全为0
38                 ValueRow_Culmn(ref row_culmn, ref row, rowup);
39                 rowup++;
40             }
41             //计算行列式的值double值不能默认等于0 否则会所有值都为零
42             double a = 1;
43             for (int i = 0; i < jlength; i++)
44             {
45                 Console.WriteLine(row_culmn[i, i]);
46                 a *= row_culmn[i, i];
47             }
48             //格式化输出
49             Console.WriteLine(string.Format("{0:F}",a));
50             Console.ReadLine();
51 
52         }
53 
54         public static void ValueRow_Culmn(ref double[,] rc, ref int row, int rowup)
55         {
56             //double jlength = Math.Sqrt(rc.Length);
57             double k;//与列相乘的系数
58             if (rowup < jlength)
59             {
60                 k = -rc[rowup, row] / rc[row, row];
61                 for (int j = 0; j < jlength; j++)
62                 {
63                     rc[rowup, j] += rc[row, j] * k;
64                 }
65 
66                 Console.WriteLine();
67                 Console.WriteLine();
68                 for (int m = 0; m < 4; m++)
69                 {
70                     for (int j = 0; j < 4; j++)
71                     {
72                         Console.Write(rc[m, j].ToString() + "  ");
73                     }
74                     Console.WriteLine();
75                 }
76 
77                 Console.WriteLine();
78                 rowup++;
79                 ValueRow_Culmn(ref rc, ref row, rowup);
80             }
81             else
82             { return; }
83         }
84 
85 
86 
87     }
88 }