# Set minimum math font size

Example:

\begin{equation}
\begin{array}{ll}
\textrm{stejne rozptyly:} & U = \frac{ \bar{x}_1 - \bar{x}_2 }{ s \sqrt{ \frac{1}{n_1} + \frac{1}{n_2} } } \\
\textrm{ruzne rozptyly:}  & U = \frac{ \bar{x}_1 - \bar{x}_2 }{ \sqrt{ \frac{s_1^2}{n_1} + \frac{s_2^2}{n_2} } }
\end{array}
\end{equation} As you can see, the font is WAY TOO small. How do I make LaTeX not print the letters smaller than say 10pt (and increase the equation row instead)?

Compiling with XeLaTeX...

EDIT: Just to be clear, I don't want a per-letter solution. I seek some global solution.

## 2 Answers

\documentclass{article}
\usepackage{mathtools}

\begin{document}
\begin{equation}\def\arraystretch{2}
\begin{array}{@{}ll}
\text{stejne rozptyly:} & U = \dfrac{ \bar{x}_1 - \bar{x}_2 }{ s \sqrt{ \dfrac{1}{n_1} + \dfrac{1}{n_2} } } \\
\text{ruzne rozptyly:}  & U = \dfrac{ \bar{x}_1 - \bar{x}_2 }{ \sqrt{ \dfrac{s_1^2}{n_1} + \dfrac{s_2^2}{n_2} } }
\end{array}
\end{equation}

\end{document} if you want it for the complete document use \let\frac\dfrac in the preamble. However using \dfrac is the safer way.

Not sure how to automatically scale your result, but you can manually set the total equation height as follows. First is your original equation. Second case is scaled to overall height of 60 pt. Third is scaled by a factor of 1.5 over the original.

In this example, I have scaled everything, including the leading text. The scalerel tools could be applied merely to the equation itself, leaving the text in the original fontsize, if you so preferred.

\documentclass{article}
\usepackage{scalerel}
\begin{document}

\def\myeqn{\begin{array}{ll}
\textrm{stejne rozptyly:} & U = \frac{ \bar{x}_1 - \bar{x}_2 }{ s \sqrt{ \frac{1}{n_1} + \frac{1}{n_2} } } \\
\textrm{ruzne rozptyly:}  & U = \frac{ \bar{x}_1 - \bar{x}_2 }{ \sqrt{ \frac{s_1^2}{n_1} + \frac{s_2^2}{n_2} } }
\end{array}}

\begin{equation}
\myeqn
\end{equation}

\begin{equation}
\scaleto{\myeqn}{60pt}
\end{equation}

\begin{equation}
\hstretch{1.5}{\vstretch{1.5}{\myeqn}}
\end{equation}

\end{document} or maybe you just mean to use \displaystyle

\begin{equation}
\begin{array}{ll}
\textrm{stejne rozptyly:} & U = \displaystyle\frac{ \bar{x}_1 - \bar{x}_2 }{ s \sqrt{ \frac{1}{n_1} + \frac{1}{n_2} } } \\
~\\
\textrm{ruzne rozptyly:}  & U = \displaystyle\frac{ \bar{x}_1 - \bar{x}_2 }{ \sqrt{ \frac{s_1^2}{n_1} + \frac{s_2^2}{n_2} } }
\end{array}
\end{equation} 