• Load arydshln after array instead of before. According to the manual, arydshln has to be loaded after array, longtable, colortab, and colortbl, respectively.

• Correct the second argument to multirow. It should be a width or a * meaning the natural width.

With these corrections, the code works:

\documentclass{article} \usepackage{array} \usepackage{arydshln} \usepackage{amsmath} \usepackage{multirow} \begin{document} \begin{align*} & \hspace{0.3cm}\overbrace{\hphantom{\begin{array}{ccc} a&b&c \end{array}}}\\ &\left[ \begin{array}{ccc:ccc:ccc} a&a&a&b&b&b&c&c&c\ \multicolumn{3}{c}{0}&\multicolumn{3}{c}{0}&\multicolumn{3}{c}{\multirow{2}{*}{0}}\\ 1&2&3&4&5&6&&&\ \end{array} \right] \end{align*} \end{document} 

Output:

• Load arydshln after array instead of before. According to the manual, arydshln has to be loaded after array, longtable, colortab, and colortbl, respectively.

• Correct the second argument to multirow. It should be a width or a * meaning the natural width.

With these corrections, the code works:

\documentclass{article} \usepackage{array} \usepackage{arydshln} \usepackage{amsmath} \usepackage{multirow} \begin{document} \begin{align*} & \hspace{0.3cm}\overbrace{\hphantom{\begin{array}{ccc} a&b&c \end{array}}}\\ &\left[ \begin{array}{ccc:ccc:ccc} a&a&a&b&b&b&c&c&c\\ \multicolumn{3}{c}{0}&\multicolumn{3}{c}{0}&\multicolumn{3}{c}{\multirow{2}{*}{0}}\\ 1&2&3&4&5&6&&&\\ \end{array} \right] \end{align*} \end{document} 

Output:

• Load arydshln after array instead of before.

• Correct the second argument to multirow. It should be a width or a * meaning the natural width.

With these corrections, the code works:

\documentclass{article} \usepackage{array} \usepackage{arydshln} \usepackage{amsmath} \usepackage{multirow} \begin{document} \begin{align*} & \hspace{0.3cm}\overbrace{\hphantom{\begin{array}{ccc} a&b&c \end{array}}}\\ &\left[ \begin{array}{ccc:ccc:ccc} a&a&a&b&b&b&c&c&c\ \multicolumn{3}{c}{0}&\multicolumn{3}{c}{0}&\multicolumn{3}{c}{\multirow{2}{*}{0}}\\ 1&2&3&4&5&6&&&\ \end{array} \right] \end{align*} \end{document} 

Output:

• Load arydshln after array instead of before. According to the manual, arydshln has to be loaded after array, longtable, colortab, and colortbl, respectively.

• Correct the second argument to multirow. It should be a width or a * meaning the natural width.

With these corrections, the code works:

\documentclass{article} \usepackage{array} \usepackage{arydshln} \usepackage{amsmath} \usepackage{multirow} \begin{document} \begin{align*} & \hspace{0.3cm}\overbrace{\hphantom{\begin{array}{ccc} a&b&c \end{array}}}\\ &\left[ \begin{array}{ccc:ccc:ccc} a&a&a&b&b&b&c&c&c\ \multicolumn{3}{c}{0}&\multicolumn{3}{c}{0}&\multicolumn{3}{c}{\multirow{2}{*}{0}}\\ 1&2&3&4&5&6&&&\ \end{array} \right] \end{align*} \end{document} 

Output: