# Multiply matrix and letter

I want to multiply a matrix with a letter, it looks like that:

\documentclass{report}

\usepackage{ngerman}
\usepackage{amsmath}
\begin{document}
$\left( \begin{array}{ccc} | & & | \\ f_1 & \dots & f_n \\ | & & | \end{array}\right) \mathcal{A} = \left( \begin{array}{ccc} | & & | \\ q_1 & \dots & q_n \\ | & & | \end{array} \right)$

\end{document}


Is there a chance, that the letter is not so small in comparison to the matrix, so that they have about the same size?

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Via graphicx package, you can use {\raisebox{-1.5ex}{\scalebox{3}{$\mathcal{A}$}}} but the result would not look that nice I guess. –  percusse Dec 4 '12 at 18:16
hm true, it looks strange. But thanks anyway. Maybe I will stick to my old variant. –  Adam Dec 4 '12 at 18:20
It would maybe look better if you reduce the size of the matrices via smallmatrix variants. –  percusse Dec 4 '12 at 18:22
thanks! that does look much better!! –  Adam Dec 4 '12 at 18:26

As percusse points out, you can resize it using the package graphicx:

{\raisebox{-1.5ex}{\scalebox{3}{$\mathcal{A}$}}}


However, I would say that it looks better "small" than "resized". That would be very inconsistent and weird. I recommend you to stuck with small $A$. However, there're few possible improvements of your code:

\documentclass{report}

\usepackage[ngerman]{babel}
\usepackage{amsmath}
\begin{document}
$\begin{pmatrix} | & & | \\ f_1 & \cdots & f_n \\ | & & | \end{pmatrix} \mathcal{A} = \begin{pmatrix} | & & | \\ q_1 & \cdots & q_n \\ | & & | \end{pmatrix}$

\end{document}

• Do not use ngerman package, use babel with the appropriate option.
• The package amsmath offers the environment pmatrix for matrices in parentheses, as well as bmatrix for [...], Bmatrix for {...}, vmatrix for |...| and Vmatrix for ||...||.
• I'm not sure what the verical bars denote (probably a vector written in a column?) but I'm sure I would not understand it as a reader. However, I don't know how to improve it, since the context is missing. If the entries are really column vectors and you defined them properly before, I think that the reader would understand it even without the bars.
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