How to use more than 10 tab stops in \bmatrix?

I'm using bmatrix environment from the amsmath package, and I'm trying to do something like this:

\documentclass{article}
\usepackage{amsmath}

\begin{document}
$$\begin{bmatrix} 1 & 2 & 3 & 4 & 5 & 6 & 7 & 8 & 9 & 10 & 11\\ \end{bmatrix}$$
\end{document}


However, pdfLaTeX returns an error: "Extra alignment tab has been changed to \cr", and in the output the extra element is moved to the next row. (If I remove one element, then it works perfectly fine). I guess this means that I've hit some hard limit on the number of tab stops in a matrix. Is there a way to change this?

The elements in the matrix are short and could fit perfectly on a single row.

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Funny enough, I looked once more after I got an answer to the question, and this latex-community.org/forum/viewtopic.php?f=46&t=5996 popped up, answered by @Stefan Kottwitz a year ago. Wish I could give him some rep for that! –  Martin Tapankov Sep 27 '10 at 11:32

2 Answers

Googling "10 columns" together with "tex" and "halign" lead me to this document, where it is explained that, e.g.,

\setcounter{MaxMatrixCols}{20}


enables you to use 20 columns.

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This is documented in the footnote on page 8 of the amsmath manual. –  Philipp Sep 27 '10 at 12:07

Yet another method is to use the array construct from amsmath package.

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

$$\left[ \begin{array}{@{}*{11}{c}@{}} 1 & 2 & 3 & 4 & 5 & 6 & 7 & 8 & 9 & 10 & 11\\ \end{array} \right]$$

\end{document}


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If you want to emulate bmatrix, you should use \begin{array}{@{}*{11}{c}@{}}. The *{11}{c} is just a convenient way to avoid counting the number of c's; the important thing is @{} at the sides, to kill the automatically inserted padding. –  egreg Apr 19 at 15:48
@egreg Many thanks, I was just thinking of adding two \!\! around the array, but your suggestion is much more elegant. –  AboAmmar Apr 19 at 15:55
The bmatrix environment indeed does \hspace{-\arraycolsep} on either ends (it's one of the reasons why the MaxMatrixCols counter is needed). –  egreg Apr 19 at 16:02