# Look for a bigger delimiter than \Bigg

\documentclass{article}
\usepackage{amsmath}
\begin{document}
$\left. \begin{vmatrix} a_{11}&a_{12}&a_{13}\\ a_{21}&a_{22}&a_{23}\\ a_{31}&a_{32}&a_{33} \end{vmatrix}\middle/\begin{vmatrix} b_{11}&b_{12}&b_{13}\\ b_{21}&b_{22}&b_{23}\\ b_{31}&b_{32}&b_{33}\\ b_{41}&b_{42}&b_{43} \end{vmatrix} \right.$
$\begin{vmatrix} a_{11}&a_{12}&a_{13}\\ a_{21}&a_{22}&a_{23}\\ a_{31}&a_{32}&a_{33} \end{vmatrix}\Bigg/\begin{vmatrix} b_{11}&b_{12}&b_{13}\\ b_{21}&b_{22}&b_{23}\\ b_{31}&b_{32}&b_{33}\\ b_{41}&b_{42}&b_{43} \end{vmatrix}$


The solidus is not fit for matrix. How can I fix it?

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You could scale / using \scalebox{<factor>}{<stuff>} from the graphicx package:

\documentclass{article}
\usepackage{amsmath}% http://ctan.org/pkg/amsmath
\usepackage{graphicx}% http://ctan.org/pkg/graphicx
\begin{document}
$\left. \begin{vmatrix} a_{11}&a_{12}&a_{13}\\ a_{21}&a_{22}&a_{23}\\ a_{31}&a_{32}&a_{33} \end{vmatrix}\middle/\begin{vmatrix} b_{11}&b_{12}&b_{13}\\ b_{21}&b_{22}&b_{23}\\ b_{31}&b_{32}&b_{33}\\ b_{41}&b_{42}&b_{43} \end{vmatrix} \right.$
$\begin{vmatrix} a_{11}&a_{12}&a_{13}\\ a_{21}&a_{22}&a_{23}\\ a_{31}&a_{32}&a_{33} \end{vmatrix}\scalebox{1.5}{\Bigg/}\begin{vmatrix} b_{11}&b_{12}&b_{13}\\ b_{21}&b_{22}&b_{23}\\ b_{31}&b_{32}&b_{33}\\ b_{41}&b_{42}&b_{43} \end{vmatrix}$
\end{document}


Note that this scales / both vertically and horizontally, increasing the width of the symbol as well. To minimize this, I've only scaled \Bigg/. To see the difference, consider (say) \raisebox{-2ex}{\scalebox{4.5}{/}}.

Another alternative could be to rotate a vertical rule by (say) 15 degrees clockwise. For this you could use

\rotatebox{-15}{\rule[-1.8\baselineskip]{0.4pt}{4\baselineskip}}


The above vertical rule has a fixed width of 0.4pt, which you can change to your liking.

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If you have access to the mtpro2 package (short for "MathTime Pro II"), you can use the following code

\documentclass{article}
\usepackage[lite]{mtpro2} % note: only "lite" subset of the mtpro2 package is needed
\usepackage{amsmath}
\begin{document}
$\PARENS{\begin{matrix} a_{11}&a_{12}&a_{13}\\ a_{21}&a_{22}&a_{23}\\ a_{31}&a_{32}&a_{33} \end{matrix}} \LEFTRIGHT/.{\PARENS{\begin{matrix} b_{11}&b_{12}&b_{13}\\ b_{21}&b_{22}&b_{23}\\ b_{31}&b_{32}&b_{33}\\ b_{41}&b_{42}&b_{43} \end{matrix}}}$
\end{document}


to produce this output:

The package's documentation states that delimiters produced with the \LEFTRIGHT<a><b> command (where the left and right hand symbols "a" and "b" can be different) can be up to 10 cm (4") tall. As shown in the example, if you need a "delimiter" on only one side, you should use a "." symbol for the other delimiter.

The full mtpro2 package is not free. However, the so-called "lite" subset of this package is indeed free of charge and may be downloaded from this website.

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The only problem is that there is no so big slash in the font. If you use \middle| or \middle( instead, the delimiter will be big enough.

If necessary, scaling as what Werner do, or use a drawing package like tikz may help.

\documentclass{article}
\usepackage{amsmath}
\usepackage{tikz}

\begin{document}
$\begin{vmatrix} a_{11}&a_{12}&a_{13}\\ a_{21}&a_{22}&a_{23}\\ a_{31}&a_{32}&a_{33} \end{vmatrix} \tikz[baseline]\draw(-1em,-2\baselineskip)--(1em,2\baselineskip); \begin{vmatrix} b_{11}&b_{12}&b_{13}\\ b_{21}&b_{22}&b_{23}\\ b_{31}&b_{32}&b_{33}\\ b_{41}&b_{42}&b_{43} \end{vmatrix}$

\end{document}

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