Reducing font in equation in slide

Question

I review some related questions:
Reducing font size in equation

But it seems that cannot work in my case (in slide).

\documentclass{beamer}
\mode<presentation>
{
  \usetheme{default}      
  \usecolortheme{default} 
  \usefonttheme{default} 
  \setbeamertemplate{navigation symbols}{}
   \setbeamertemplate{caption}[numbered]
} 
\setbeamertemplate{frametitle}[default][center]
\usepackage[english]{babel}
\usepackage[utf8x]{inputenc}
\usepackage{amsmath}

\begin{document}
\begin{frame}{$\mathcal{A}_d$ and $\mathcal{A}_d^*$}
\begin{itemize}
\item $\mathcal{A}_d: \mathcal{S}^4 \rightarrow \mathbf{R}^{3\times 3}$  


\begin{equation*}
\begin{aligned}
\mathcal{A}(Z) = \begin{bmatrix} Z_{11}-Z_{22}-Z_{33}+Z_{44} & 2Z_{12}+2Z_
{34} & 2Z_{13}-2Z_{24} \\ 2Z_{12}-2Z_{34} & -Z_{11}+Z_{22}-Z_{33}+Z_{44}&      
2Z_{23}+2Z_{14} \\ 2Z_{13}+2Z_{24} & 2Z_{23}-2Z_{14}  & -Z_{11}-Z_{22}+Z_{33}+Z_{44}  
\end{bmatrix}
\end{aligned}
\end{equation*}

\item $\mathcal{A}_d^*: \mathbf{R}^{3\times 3} \rightarrow  \mathcal{S}^4  $
\end{itemize}
\end{frame}
\end{document}  

It shows (it should be a 4 by 4 matrix.)

How could I choose the size of font in the equation such that all elements of matrix show up? (only for this case not for all slides)

Answer 1

You can use the {\tiny ... } before your aligned environment:

\documentclass{beamer}
\mode<presentation>
{
  \usetheme{default}      
  \usecolortheme{default} 
  \usefonttheme{default} 
  \setbeamertemplate{navigation symbols}{}
   \setbeamertemplate{caption}[numbered]
} 
\setbeamertemplate{frametitle}[default][center]
\usepackage[english]{babel}
\usepackage[utf8x]{inputenc}
\usepackage{amsmath}

\begin{document}
\begin{frame}{$\mathcal{A}_d$ and $\mathcal{A}_d^*$}
\begin{itemize}
\item $\mathcal{A}_d: \mathcal{S}^4 \rightarrow \mathbf{R}^{3\times 3}$  


\begin{equation*}
{\tiny  
  \setlength{\abovedisplayskip}{6pt}
  \setlength{\belowdisplayskip}{\abovedisplayskip}
  \setlength{\abovedisplayshortskip}{0pt}
  \setlength{\belowdisplayshortskip}{3pt}
\begin{aligned}
\mathcal{A}(Z) = \begin{bmatrix} Z_{11}-Z_{22}-Z_{33}+Z_{44} & 2Z_{12}+2Z_
{34} & 2Z_{13}-2Z_{24} \\ 2Z_{12}-2Z_{34} & -Z_{11}+Z_{22}-Z_{33}+Z_{44}&      
2Z_{23}+2Z_{14} \\ 2Z_{13}+2Z_{24} & 2Z_{23}-2Z_{14}  & -Z_{11}-Z_{22}+Z_{33}+Z_{44}  
\end{bmatrix}
\end{aligned}
}
\end{equation*}

\item $\mathcal{A}_d^*: \mathbf{R}^{3\times 3} \rightarrow  \mathcal{S}^4  $
\end{itemize}
\end{frame}
\end{document}