# Equal font sizes in equation while using Beamer

This is a follow-up question to Equations, change the font size

I was trying to have equal font sizes in equations like the ones in the above link. Using \DeclareMathSizes{display size}{text size}{script size}{subscript size} gives me desired effects in article, exam classes but no effect in beamer slides.

Any suggestion please to see the effects in beamer slides!

My MWE is:

\documentclass{beamer}
\usetheme{Warsaw}
\DeclareMathSizes{12}{24}{24}{24}
\begin{document}

\begin{frame}
\frametitle{test equation to have a same font size}
$x = \frac{1}{x + \frac{1}{x + \frac{1}{x}}}$
\end{frame}

\end{document}


and its output is:

-
Add the 12pt class option as in my example: \documentclass[12pt]{beamer}, or use \makeatletter\DeclareMathSizes{\@xipt}{24}{24}{24}\makeatother as egreg suggested. . –  Gonzalo Medina Sep 20 '12 at 13:47
@Gonzalo Medina, Oh sorry, yes, it works after putting 12pt in class option. Thank you so much for the help. –  Khaaba Sep 21 '12 at 5:34

The default text size used by beamer is 11pt, which must be referred to as \@xipt. Just for an example I tried very big math font sizes, using the Arev fonts to overcome problems in font loading:

\documentclass{beamer}
\usepackage[T1]{fontenc}
\usepackage{arevtext,arevmath}
\usefonttheme{professionalfonts}

\makeatletter
\DeclareMathSizes{\@xipt}{50}{40}{30}
\makeatother

\begin{document}
\begin{frame}
Text $m_{a}+t+\sqrt{h}$
\end{frame}
\end{document}


Similar declarations should be made for the other sizes, if you plan to use math in \large, \small or similar contexts.

However, I don't think that changing the math sizes is a good thing to do.

After seeing the minimal example and the real problem you have, I suggest you to use the \cfrac command provided by amsmath.

\documentclass{beamer}
\usetheme{Warsaw}
\usepackage{amsmath}
\begin{document}

\begin{frame}
\frametitle{test equation to have a same font size}
$x = \cfrac{1}{x + \cfrac{1}{x + \cfrac{1}{x}}}$
\end{frame}

\end{document}


-
thank you for reply. –  Khaaba Sep 20 '12 at 14:21

While methods given by @GonzaloMedina and @egreg work perfectly fine in cases, I have also found another method from wikibook from here-> http://en.wikibooks.org/wiki/LaTeX/Advanced_Mathematics. Very handy to use command: \everymath{\displaystyle} in the preamble. You can also use in the localized equation like:

$$x = a_0 + \frac{1}{\displaystyle a_1 + \frac{1}{\displaystyle a_2 + \frac{1}{\displaystyle a_3 + a_4}}}$$


Note: \DeclareMathSizes{display size}{text size}{script size}{subscript size} failed in one of my big beamer file which has tikz along with many other packages.

-
You should check the \cfrac macro provided by amsmath. For this application \DeclareMathSizes is clearly overkill. –  egreg Sep 27 '12 at 14:10
@egreg, thank you. I saw that too just now in amsmdoc. Yes, \DeclareMathSizes makes overlapping of numerator and denominator expressions sometimes. –  Khaaba Sep 27 '12 at 14:32

You can use the same method as customizing the normal text size ...

\fontsize{9.5}{7.2}{
$$\psi = \psi^{s}+\tilde{\psi}$$
}

-
Should this be a comment to one of the answers? Or what is ment with "same method here"? –  Kurt Aug 8 '13 at 14:36