Multiply matrix and letter

Question

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?

Answer 1

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.