由于 StackExchange 上一些帖子的帮助（主要是 [1] 和 [2]），我认为我掌握了在 TikZ 中用括号对矩阵行和列进行分类并用线条分隔它们的要点。但是，我无法使 draw 命令中的位置引用起作用，奇怪的是，只能在某些矩阵内起作用。链接中的示例（4x4 矩阵）编译完美，但下面更大的矩阵却不能。（我只将示例中较小的矩阵与较大的矩阵进行了交换。）
\begin{tikzpicture}[decoration=brace,every left delimiter/.style={xshift=3pt},
every right delimiter/.style={xshift=-3pt},node distance=-1ex]
\matrix [matrix of math nodes,left delimiter=(,right delimiter=),
row sep=0.5cm,column sep=0.5cm] (m) {
x & x & \otimes & x & x & x & & & & & & & \\
& & & \otimes & x & & x & x & & x & & & \\
x & & x & & \otimes & & & & & & & & \\
& & & & & \otimes & x & & & & & x & \\
& & & & & & \otimes & x & & & & x & \\
& & & & & & x & \otimes & & x & & & \\
& & & & & & & & \otimes & x & & & \\
& & & & & & & & x & \otimes & x & & \\
& & & & & & & & & & \otimes & x & \\
& & & & & & & & & & & \otimes & \\
& & & & & & & & & & x & & \\
& & & & & & & & & & x & x & \\
& & & & & & & & & & & x & \\};
\draw[dashed] ($0.5*(m-1-2.north east)+0.5*(m-1-3.north west)$) --
($0.5*(m-4-2.south east)+0.5*(m-4-3.south west)$);
\draw[dashed] ($0.5*(m-2-1.south west)+0.5*(m-3-1.north west)$) --
($0.5*(m-2-4.south east)+0.5*(m-3-4.north east)$);
\node[above=10pt of m-1-1] (top-1) {a};
\node[above=10pt of m-1-2] (top-2) {b};
\node[above=10pt of m-1-3] (top-3) {c};
\node[above=10pt of m-1-4] (top-4) {d};
\node[left=12pt of m-1-1] (left-1) {$\alpha$};
\node[left=12pt of m-2-1] (left-2) {$\beta$};
\node[left=12pt of m-3-1] (left-3) {$\gamma$};
\node[left=12pt of m-4-1] (left-4) {$\delta$};
\node[rectangle,above delimiter=\{] (del-top-1) at ($0.5*(top-1.south) +0.5*(top-2.south)$) {\tikz{\path (top-1.south west) rectangle (top-2.north east);}};
\node[above=10pt] at (del-top-1.north) {$A$};
\node[rectangle,above delimiter=\{] (del-top-2) at ($0.5*(top-3.south) +0.5*(top-4.south)$) {\tikz{\path (top-3.south west) rectangle (top-4.north east);}};
\node[above=10pt] at (del-top-2.north) {$B$};
\node[rectangle,left delimiter=\{] (del-left-1) at ($0.5*(left-1.east) +0.5*(left-2.east)$) {\tikz{\path (left-1.north east) rectangle (left-2.south west);}};
\node[left=10pt] at (del-left-1.west) {$C$};
\node[rectangle,left delimiter=\{] (del-left-2) at ($0.5*(left-3.east) +0.5*(left-4.east)$) {\tikz{\path (left-3.north east) rectangle (left-4.south west);}};
\node[left=10pt] at (del-left-2.west) {$D$};
\end{tikzpicture}
具体来说，我收到错误消息“！Package pgf 错误：没有已知名为 m-4-2 的形状。”，该消息出现在绘制虚线的第一行。但是，名为 m-1-3 和 m-1-2 的形状是已知的。我在这里不知所措，因为我无法将错误与可能出错的代码联系起来。
答案1
将选项添加nodes in empty cells到矩阵，以便能够引用这些节点：
\matrix [matrix of math nodes, left delimiter=(,right delimiter=),
row sep=0.5cm, column sep=0.5cm, nodes in empty cells] (m) { ...