bordermatrix with blocks

Question

I need to write a complicated matrix, that has a structure as in the attached picture.

Answer 1

The blkarray package allows to do complex border matrix with relatively simple code:

\documentclass{article}

\usepackage{blkarray}
\usepackage{multirow}

\begin{document}

\[
  \begin{blockarray}{cc|cccc|cccc}
    & 1\dots 18 & 19 & 20 & 21 & 22 & 23 & 24 & 25 & 26 \\
    \begin{block}{c(c|cccc|cccc@{\hspace*{5pt}})}
    A'_1 & A_1 & \BAmulticolumn{4}{c|}{\multirow{4}{*}{$I$}}&\BAmulticolumn{4}{c}{\multirow{4}{*}{$I$}}\\
    A'_2 & A_2 & &&&&&&&\\
    A'_3 & A_3 & &&&&&&&\\
    A'_4 & A_4 & &&&&&&&\\
    \cline{1-10}% don't use \hline
    B'_1 & B_1 & \BAmulticolumn{4}{c|}{\multirow{4}{*}{$J$}}&\BAmulticolumn{4}{c}{\multirow{4}{*}{$I$}}\\
    B'_2 & B_2 & &&&&&&&\\
    B'_3 & B_3 & &&&&&&&\\
    B'_4 & B_4 & &&&&&&&\\
    \end{block}
  \end{blockarray}
\]

\end{document}

Answer 2

\documentclass{article}
\usepackage{blkarray}
\def\Big#1{\makebox(0,0){\huge#1}}

\begin{document}

\[
\begin{blockarray}{cc|c|c}
 & 1\ldots18&19\,20\,21\,22&23\,24\,25\,26\\ 
 \begin{block}{c(c|c|c)}
   A_1^\prime & A_1 &        &        \\  
   A_2^\prime & A_2 & \Big{I}& \Big{I}\\  
   A_3^\prime & A_3 &        &        \\
   A_4^\prime & A_4 &        &        \\\cline{1-4}
   B_1^\prime & B_1 &        &        \\  
   B_2^\prime & B_2 &\Big{J} & \Big{I}\\  
   B_3^\prime & B_3 &        &        \\  
   B_4^\prime & B_4 &        &        \\  
 \end{block}
\end{blockarray}
\]
\end{document}

Answer 3

Thanks to everyone. I managed to find solution myself as well. I have used package kbordermatrix. However very often math journals want to typeset the tex file themselves and they don't have all the packages. I'm sure that at least one variant will work. So thank again:) My solution is below:

\documentclass{article}
\usepackage{kbordermatrix}
\begin{document}

\begin{equation}
\kbordermatrix{
& 1 \ldots 18 & \vrule & 19 \text{ } 20 \text{ } 21 \text{ } 22 & \vrule & 23 \text{ }  24 \text{ } 25 \text{ } 26 \\           
  \begin{array}{c} \chi(A'_1) \\ \chi(A'_2) \\ \chi(A'_3) \\ \chi(A'_4) \end{array}
& \begin{array}{c} \chi(A_1)  \\ \chi(A_2)  \\ \chi(A_3)  \\ \chi(A_4)  \end{array}
& \vrule & I & \vrule& I \\ \hline
  \begin{array}{c} \chi(B'_1) \\ \chi(B'_2) \\ \chi(B'_3) \\ \chi(B'_4) \end{array}
& \begin{array}{c} \chi(B_1)  \\ \chi(B_2)  \\ \chi(B_3)  \\ \chi(B_4)  \end{array}
& \vrule & J & \vrule& I  } , 
\end{equation}
\end{document}

Answer 4

Plain-kru represenz:

\font\Large=cmr10 at 20pt
\newcount\rowcount\rowcount=3
\def\fudge#1{\smash{\hbox{\Large#1}}}
\def\doublyso{\kern-.5em\smash{\vrule height \rowcount em depth .2em}\hidewidth}
$\bordermatrix{
  \global\everycr{\noalign{\global\advance\rowcount by 1}}
  &1\ldots18&19\;20\;21\;22&23\;24\;25\;26 \cr
  A_1'&A_1\cr
  A_2'&A_2\cr
  A_3'&A_3&\fudge I&\fudge I\cr
  A_4'&A_4\cr
  \noalign{\smallskip\hrule\smallskip}
  B_1'&B_1\cr
  B_2'&B_2\cr
  B_3'&B_3&\fudge J&\fudge I\cr
  B_4'&B_4&\doublyso&\doublyso\cr
}$
\everycr={}
\bye

In my "imitation of \atopwithdelims-line of thought"-spree, I made one for \bordermatrix as well (which is the Plain \bordermatrix with only the delims made as arguments):

\catcode`@=11
\def\bordermatrixwithdelims#1#2#3{\begingroup \m@th
  \setbox0=\vbox{\def\cr{\crcr\noalign{\kern2pt\global\let\cr=\endline}}
    \ialign{$##$\hfil\kern2pt\kern\p@renwd&\thinspace\hfil$##$\hfil
      &&\quad\hfil$##$\hfil\crcr
      \omit\strut\hfil\crcr\noalign{\kern-\baselineskip}
      #3\crcr\omit\strut\cr}}
  \setbox2=\vbox{\unvcopy0 \global\setbox1=\lastbox}
  \setbox2=\hbox{\unhbox1 \unskip \global\setbox1=\lastbox}
  \setbox2=\hbox{$\kern\wd1\kern-\p@renwd \left#1 \kern-\wd1
    \global\setbox1=\vbox{\box1\kern2pt}
    \vcenter{\kern-\ht1 \unvbox0 \kern-\baselineskip} \,\right#2$}
  \null\;\vbox{\kern\ht1\box2}\endgroup}
\catcode`@=12
%
\def\cbordermatrix#1{\bordermatrixwithdelims[]{#1}}
\def\bbordermatrix#1{\bordermatrixwithdelims\{\}{#1}}
\def\vbordermatrix#1{\bordermatrixwithdelims||{#1}}
%
$$
\bordermatrix{&[a]&[b]\cr &1&2\cr&3&4}
\cbordermatrix{&[a]&[b]\cr &1&2\cr&3&4}
\bbordermatrix{&[a]&[b]\cr &1&2\cr&3&4}
\vbordermatrix{&[a]&[b]\cr &1&2\cr&3&4}
$$
\bye

So to achieve the look of which the OP settled on, one could just substitute the call to \bordermatrix in my original answer with \cbordermatrix

Answer 5

You can use multirow and bigdelim package for this matrix. Example:

\documentclass{article}
\usepackage{multirow,bigdelim}
\begin{document}
\[
\begin{array}{ccc|cc|ccc}
  && x & a & b & c & d \\
A &\ldelim({4}{0.5em}& x
  & \multicolumn{2}{c|}{\multirow{2}*{ab}}
  & \multicolumn{2}{c}{\multirow{2}*{cd}}
  & \rdelim){4}{0.5em} \\
B && y &&&& \\
\hline
C && x 
  & \multicolumn{2}{c|}{\multirow{2}*{ab}}
  & \multicolumn{2}{c}{\multirow{2}*{cd}} \\
D && y &&&& \\
\end{array}
\]
\end{document}