latex 矩阵

如何用latex编写矩阵（包括各类复杂、大型矩阵）？

分块矩阵

\begin{equation*}
        \begin{array}{c@{\hspace{-5pt}}l}   
            \left(\begin{array}{ccc:ccc}    
                a&\cdots &a &b &\cdots&b\\  
                &\ddots &\vdots &\vdots &\vdots\\   
                & &a& b \\\hline    
                & & & c &\cdots &c\\    
                & & & \vdots& &\vdots\\ 
                \multicolumn{3}{c|}{\raisebox{2ex}[0pt]{\Huge0}}
                & c & \cdots & c    
            \end{array}\right)  
            &\begin{array}{l}\left.\rule{0mm}{7mm}\right\}p\\   
                \\\left.\rule{0mm}{7mm}\right\}q    
            \end{array}\\[-5pt] 
            \begin{array}{cc}\underbrace{\rule{17mm}{0mm}}_m&
                \underbrace{\rule{17mm}{0mm}}_m\end{array}& 
        \end{array}
    \end{equation*}

效果：

2