比来学习机器学习 才发明以前数学没有学好 开始从线性代数开始学起 读完行列式一章写了些C#的代码学习一下。
直接上C#代码：
using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Runtime.InteropServices; using System.IO; namespace LYF.Math { /// <summary> /// 行列式 Determinant /// </summary> [SerializableAttribute] [ComVisibleAttribute(true)] public class Determinant<T> where T : IComparable, IFormattable, IConvertible, IComparable<T>, IEquatable<T> { T[,] tarr = null; public Determinant(int n) { tarr = new T[n, n]; } public Determinant(T[,] arrT) { if (arrT == null || arrT.GetLength(0) != arrT.GetLength(1) || arrT.GetLength(0) < 1) { throw new MathException("不正确的数组（数组必需行列数不异且大于1）"); } else { tarr=new T[arrT.GetLength(0),arrT.GetLength(0)]; SetItem(arrT); } } /// <summary> /// 获取元素值 /// </summary> /// <param></param> /// <param></param> /// <returns></returns> public T this[int i, int j] { //实现索引器的get要领 get { return GetItem(i, j); } //实现索引器的set要领 set { SetItem(i, j, value); } } /// <summary> /// 获取元素的余子式 /// </summary> /// <param></param> /// <param></param> /// <returns></returns> public Determinant<T> A(int i, int j) { if (N == 1) { return null; } else if (i>N||j>N) { return null; } else { Determinant<T> a = new Determinant<T>(N - 1); for (int m = 1; m <= N - 1; m++) { for (int n = 1; n <= N - 1; n++) { int p = m, q = n; if (p >= i) { p = m + 1; } if (q >= j) { q = n + 1; } a[m, n] = this[p,q]; } } return a; } } /// <summary> /// 设置行列式的值 /// </summary> /// <param>行数（从1开始）</param> /// <param>列数（从1开始）</param> /// <param>值</param> public void SetItem(int i, int j, T value) { if (tarr == null) { throw new MathException("行列式未正确初始化"); } else if (i > N || j > N) { throw new MathException("超过行列式索引范畴"); } else { tarr[i - 1, j - 1] = value; } } public void SetItem(T[,] arrT) { if (arrT == null || tarr == null) { throw new MathException("不能为空"); } else if (arrT.GetLength(0) != N || arrT.GetLength(1) != N) { throw new MathException("传入阶数差别"); } else { for (int m = 0; m <=N-1; m++) { for (int n = 0; n <= N- 1; n++) { this[m + 1, n + 1] = arrT[m, n]; } } } } /// <summary> /// 设置行列式的值 /// </summary> /// <param>行数（从1开始）</param> /// <param>列数（从1开始）</param> /// <param>值</param> public T GetItem(int i, int j) { if (tarr == null) { throw new MathException("行列式未正确初始化"); } else if (i > N || j > N) { throw new MathException("超过行列式索引范畴"); } else { return tarr[i-1, j-1]; } } /// <summary> /// 输出行列式信息 /// </summary> /// <returns></returns> public override string ToString() { StringBuilder sbRs = new StringBuilder(); if(tarr!=null) { for (int m = 0; m <= N - 1; m++) { for (int n = 0; n <= N - 1; n++) { sbRs.Append(string.Format("{0}\t", tarr[m, n])); } sbRs.Append("\n"); } } return sbRs.ToString(); } /// <summary> /// 获取行列式的阶数 /// </summary> public int N { get{ if (tarr != null) { return tarr.GetLength(0); } else { return 0; } } } private string typeName = string.Empty; private string GetType() { if (string.IsNullOrEmpty(typeName)) { typeName=typeof(T).Name; File.AppendAllText("E:\\op.txt", typeName); } return typeName; } /// <summary> /// 获取行列式的值 /// </summary> public T Value { get { if (N == 1) { return tarr[0, 0]; } else if (N == 2) { return Minus(MUL(tarr[0, 0], tarr[1, 1]), MUL(tarr[0, 1], tarr[1, 0])); } else { T sum = default(T); for (int i = 1; i <= N; i++) { if ((1+i) % 2 == 0) { //余子式正值 sum = Add(sum, MUL(this[1, i], this.A(1, i).Value)); } else { //余子式负值 sum = Minus(sum, MUL(this[1, i], this.A(1, i).Value)); } } return sum; } } } /// <summary> /// 加法 /// </summary> /// <param></param> /// <param></param> /// <returns></returns> private T Add(T left, T right) { switch (GetType()) { case "Int16": return ((T)(object)((short)(object)left + (short)(object)right)); case "Int32": return ((T)(object)((int)(object)left + (int)(object)right)); case "Int64": return ((T)(object)((long)(object)left + (long)(object)right)); case "Single": return ((T)(object)((float)(object)left + (float)(object)right)); case "Double": return ((T)(object)((double)(object)left + (double)(object)right)); case "Decimal": return ((T)(object)((decimal)(object)left + (decimal)(object)right)); } throw new MathException("不撑持的操纵类型"); } /// <summary> /// 减法 /// </summary> /// <param></param> /// <param></param> /// <returns></returns> private T Minus(T left, T right) { switch (GetType()) { case "Int16": return ((T)(object)((short)(object)left - (short)(object)right)); case "Int32": return ((T)(object)((int)(object)left - (int)(object)right)); case "Int64": return ((T)(object)((long)(object)left - (long)(object)right)); case "Single": return ((T)(object)((float)(object)left - (float)(object)right)); case "Double": return ((T)(object)((double)(object)left - (double)(object)right)); case "Decimal": return ((T)(object)((decimal)(object)left - (decimal)(object)right)); } throw new MathException("不撑持的操纵类型"); } /// <summary> /// 乘法 /// </summary> /// <param></param> /// <param></param> /// <returns></returns> private T MUL(T left, T right) { switch (GetType()) { case "Int16": return ((T)(object)((short)(object)left * (short)(object)right)); case "Int32": return ((T)(object)((int)(object)left * (int)(object)right)); case "Int64": return ((T)(object)((long)(object)left * (long)(object)right)); case "Single": return ((T)(object)((float)(object)left * (float)(object)right)); case "Double": return ((T)(object)((double)(object)left * (double)(object)right)); case "Decimal": return ((T)(object)((decimal)(object)left * (decimal)(object)right)); } throw new MathException("不撑持的操纵类型"); } } }