C#矩阵运算：快速乘法、求逆与校验

#region double[,]
        public static bool Equal(this double[,] owner, double[,] target) {
            var r = false;
            var len0 = owner.GetLength(0); var len1 = owner.GetLength(1);
            if (owner.Length == target.Length && len0 == target.GetLength(0) && len1 == target.GetLength(1)) {
                return false;
            }
            for (int i = 0; i < len0; i++) {
                for (int j = 0; j < len1; j++) {
                    if (owner[i, j] != target[i, j]) {
                        r = false; break;
                    }
                }
            }
            return r;
        }
        /// <summary>
        /// 矩阵乘
        /// </summary>
        /// <param name="left"></param>
        /// <param name="right"></param>
        /// <returns></returns>
        public static double[,] Mul(this double[,] left, double[,] right) {
            //判断行列是否匹配
            var len1 = left.GetLength(0); var len2 = right.GetLength(1);
            var len3 = left.GetLength(1); var len4 = right.GetLength(0);
            if (len3 != len4)
                throw new Exception("乘法条件不匹配，请确保前行后列长度相等");
            var x1 = new double[len1, len1];
            for (int k = 0; k < len2; k++) {

                for (int i = 0; i < len1; i++) {
                    for (int j = 0; j < len4; j++) {
                        x1[i, k] += left[i, j] * right[j, k];
                    }
                }
            }
            return x1;
        }
        //
        /// <summary>
        /// 矩阵的逆
        /// </summary>
        /// <param name="target"></param>
        /// <returns></returns>
        public static double[,] Inverse(this double[,] target) {
            if (target.GetLength(0) != target.GetLength(1)) {
                throw new Exception("只有方阵才有逆");
            }
            var level = target.GetLength(0);
            double dMatrixValue = MatrixValue(target, level);
            if (dMatrixValue == 0) return null;
            double[,] dReverseMatrix = new double[level, 2 * level];
            double x, c;
            // Init Reverse matrix
            for (int i = 0; i < level; i++) {
                for (int j = 0; j < 2 * level; j++) {
                    if (j < level)
                        dReverseMatrix[i, j] = target[i, j];
                    else
                        dReverseMatrix[i, j] = 0;