# font size needs to be reduced

How can I adjust the size of subscripts showing dimension of these matrices in following code.

Is there anything other than \tiny{.} that can be used for this purpose?

\documentclass{beamer}
\usepackage{amsmath}
\newcommand*{\vertbar}{\rule[1ex]{0.5pt}{2.5ex}}
\newcommand*{\horzbar}{\rule[.5ex]{2.5ex}{0.5pt}}

\begin{document}

\begin{frame}
\begin{align*}
\boldsymbol{A} =
\left[
\begin{array}{ccc}
\horzbar & \boldsymbol{a}_{1}^{\tiny{T}} & \horzbar\\
\horzbar & \boldsymbol{a}_{2}^{\tiny{T}} & \horzbar\\
& \vdots & \\
\horzbar & \boldsymbol{a}_{k_1}^{\tiny{T}} & \horzbar
\end{array}
\right]_{\tiny{ k_1 \times k_2}}\implies
vec (\boldsymbol{A}) =
\left[
\begin{matrix}
\boldsymbol{a}_{1}^{\tiny{T}}   & \boldsymbol{a}_{2}^{\tiny{T}}       & \cdots   & \boldsymbol{a}_{k_1}^{\tiny{T}}
\end{matrix}
\right]_{\tiny{k_1 k_2 \times 1}}^T
\end{align*}
\end{frame}
\end{document}

• Your \tiny commands do nothing, except filling your log file with warnings Command \tiny invalid in math mode. What adjustment would you like? – egreg Aug 17 '15 at 19:58
• Oh...so what should I use to make 'T' (transpose operator) small? Actually I wanted to get reduce the space between end of matrix A and implies sign. I thought that making dimension font small will do the job. – NAASI Aug 17 '15 at 20:18
• It is already smaller. – egreg Aug 17 '15 at 20:20
• You might be interested in tex.stackexchange.com/questions/30619/… – John Kormylo Aug 17 '15 at 22:11
• Also, \tiny doesn't take an argument even when it is used correctly in text mode. It is a font switch. Try putting \tiny{hello} world to see what I mean. – cfr Aug 17 '15 at 23:19