[latex]\left(\begin{array}{c}\begin{array}{ccccc}b_{1j}&&&&\\&\ddots&&&\\&&b_{1j}&&\\&&&\ddots&\\&&&&b_{1j}\end{array}\\\begin{array}{ccccc}\cdots&\cdots&\cdots&\cdots&\cdots\end{array}\\\begin{array}{ccccc}&&\vdots&&\end{array}\\\begin{array}{ccccc}\cdots&\cdots&\cdots&\cdots&\cdots\end{array}\\\begin{array}{ccccc}b_{2j}&&&&\\&\ddots&&&\\&&b_{2j}&&\\&&&\ddots&\\&&&&b_{2j}\end{array}\end{array}\right)+\left(\begin{array}{c}\begin{array}{ccccc}b_{3j}&&&&\\&\ddots&&&\\&&b_{3j}&&\\&&&\ddots&\\&&&&b_{3j}\end{array}\\\begin{array}{ccccc}\cdots&\cdots&\cdots&\cdots&\cdots\end{array}\\\begin{array}{ccccc}&&\vdots&&\end{array}\\\begin{array}{ccccc}\cdots&\cdots&\cdots&\cdots&\cdots\end{array}\\\begin{array}{ccccc}b_{4j}&&&&\\&\ddots&&&\\&&b_{4j}&&\\&&&\ddots&\\&&&&b_{4j}\end{array}\end{array}\right)[/latex]

2楼: Originally posted by 量张 at 2015-12-28 15:43:32
忘了加图，图在这

\[\left({\begin{array}{*{20}{c}}{{a_{11}}}&\ldots&{\overbrace{{a_{1n}}}^{}}\\\vdots&\ddots&\vdots\\{{a_{m1}}}&\cdots&{{a_{mn}}}\end{array}}\right)\]