降階法計算行列式方法有個地方有Bug（原文也已更正，此為更正後部分）

今天用此函數做方程求解時發現有誤，特此更正：

/// 

        /// 降階法計算行列式
        /// 
        /// N階行列式
        /// 是否0優化
        /// 計算結果
        public static decimal CalcDeterminantAij(decimal[,] Determinants, bool ZeroOptimization = false)
        {
            var theN = Determinants.GetLength(0);
            //如果為2階，直接計算
            if (theN == 2)
            {
                return Determinants[0, 0] * Determinants[1, 1] - Determinants[0, 1] * Determinants[1, 0];
            }
            if (theN == 1)
            {
                return Determinants[0, 0];
            }
            if (theN == 0)
            {
                throw new Exception("參數錯誤!");
            }
            if (ZeroOptimization)
            {
                //找0最多的行
                int theRowIndex = 0;
                int theMaxZeroCountR = -1;
                for (int i = 0; i < theN; i++)
                {
                    int theZeroNum = 0;
                    for (int j = 0; j < theN; j++)
                    {
                        if (Determinants[i, j] == 0)
                        {
                            theZeroNum++;
                        }
                    }
                    if (theZeroNum > theMaxZeroCountR)
                    {
                        theRowIndex = i;
                        theMaxZeroCountR = theZeroNum;
                    }
                }
                //找0最多的列
                int theColIndex = 0;
                int theMaxZeroCountC = -1;
                for (int i = 0; i < theN; i++)
                {
                    int theZeroNum = 0;
                    for (int j = 0; j < theN; j++)
                    {
                        if (Determinants[j, i] == 0)
                        {
                            theZeroNum++;
                        }
                    }
                    if (theZeroNum > theMaxZeroCountC)
                    {
                        theColIndex = i;
                        theMaxZeroCountC = theZeroNum;
                    }
                }
                if (theMaxZeroCountR >= theMaxZeroCountC)
                {
                    decimal theRetDec = 0;
                    //第i=theRowIndex+1行展開
                    int i = theRowIndex + 1;
                    for (int j = 1; j <= theN; j++)
                    {
                        var theSign = CalcDeterMijSign(i, j);
                        var theNewMij = GetDeterminantMij(Determinants, i, j);
                        theRetDec += theSign * Determinants[i - 1, j - 1] * CalcDeterminantAij(theNewMij, ZeroOptimization);
                    }
                    return theRetDec;
                }
                else
                {
                    decimal theRetDec = 0;
                    //第j=theColIndex+1列展開
                    int j = theColIndex + 1;
                    for (int i = 1; i <= theN; i++)
                    {
                        var theSign = CalcDeterMijSign(i, j);
                        var theNewMij = GetDeterminantMij(Determinants, i, j);
                        theRetDec += theSign * Determinants[i, j] * CalcDeterminantAij(theNewMij, ZeroOptimization);
                    }
                    return theRetDec;
                }
            }
            else
            {
                //采用隨機法展開一行
                var i = new Random().Next(1, theN);
                decimal theRetDec = 0;
                for (int j = 1; j <= theN; j++)
                {
                    var theSign = CalcDeterMijSign(i, j);
                    var theNewMij = GetDeterminantMij(Determinants, i, j);
                    //此處修改theRetDec += theSign * Determinants[i, j] * CalcDeterminantAij(theNewMij, ZeroOptimization);
                    theRetDec += theSign * Determinants[i-1, j-1] * CalcDeterminantAij(theNewMij, ZeroOptimization);
                }
                return theRetDec;
            }
        }