# Concatenation of matrices

I could not find anywhere my problem: I wanna write in LateX the following drawing. It is a matrix made of submatrices, which elements contains the elements of near matrices

Had fun writing the description. Thanks a lot, Davide

• Welcome to TeX.SX! it is common practice to (try to) provide a minimal working example (MWE) that illustrates your problem. Questions posting just an image sounds a lot like "please do it for me" Commented May 14, 2020 at 20:48
• Yeah, I tried it but the best I could do was to obtain a normal matrix with some inside. Sorry! Commented May 14, 2020 at 20:50

Welcome! Just make the distance between the rows negative.

\documentclass{article}
\usepackage{amsmath}
\begin{document}
$\begingroup\setlength\arraycolsep{2pt} \begin{bmatrix} [ & &]& & & \\[-1.4ex] & [&&] & & \\[-1.4ex] & &[& &] & \\ & & & & & \ddots\\ \end{bmatrix}\endgroup$
\end{document}


• Thank you a lot!! Commented May 14, 2020 at 20:50

You can make TeX do the computations.

\documentclass{article}
\usepackage{amsmath}

\DeclareFontShape{OMX}{cmex}{b}{n}{<->cmexb10}{}
\SetSymbolFont{largesymbols}{bold}{OMX}{cmex}{b}{n}

\begin{document}

\begin{bmatrix} \, \hbox{\boldmath\valign{% #\cr \hbox{\!\Big[}\vfill\cr\noalign{\quad} \vfill\hbox{\!\Big[}\vfill\cr\noalign{\quad} \hbox{\Big]\!}\vspace{2pt}\hbox{\!\Big[}\cr\noalign{\quad} \vfill\hbox{\Big]\!}\vfill\cr\noalign{\quad} \vfill\hbox{\Big]\!}\cr }} \\ &\ddots \end{bmatrix}

\end{document}


Apart from \valign, the trick is to notice that the brackets are placed symmetrically in their bounding box, but happily the “blank” part turns out to be 3mu, so it can be removed with \!.

Another trick is to enable bold large symbols.