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latexbeamer

Scale an equation* to fit exact page width

I have a beamer presentation with lots of equations that are too big for a line.
I want to automatically scale them to fit.
The solution to Scale an equation to fit exact page width by https://stackoverflow.com/users/3383640/suuuehgi was great.

However I do not want equation numbers - I want this same resizing to apply to all equation* bits.
I can't figure out how to adjust the code to deal with this. Help much appreciated!

Solution

  • The following code uses a slightly improved approach, noting that content within a display equation is set using \displaystyle (not contained within the measurement in the linked answer). In principle, the approach is the same:

    • The content is measured horizontally.
    • The content is resized to fit if it is wider than \linewidth.

    The equation* shorthand is redefined to also accommodate this new approach.

    enter image description here

    \documentclass{beamer}

\usepackage{environ}

\newlength{\myl}
\expandafter\let\expandafter\origequation\csname equation*\endcsname
\expandafter\let\expandafter\endorigequation\csname endequation*\endcsname
\long\def\[#1\]{\begin{equation*}#1\end{equation*}}
\RenewEnviron{equation*}{
  \settowidth{\myl}{$\displaystyle\BODY$} % calculate width and save as \myl
  \origequation
    \ifdim\myl>\linewidth
      \resizebox{\linewidth}{!}{$\displaystyle\BODY$}% \myl > \linewidth
    \else
      \BODY % \myl <= \linewidth
    \fi
  \endorigequation
}

\begin{document}

\begin{frame}
  \begin{equation*}
    f(x) = ax^2 + bx + c
  \end{equation*}
  
  \begin{equation*}
    g(x) = ax^2 + bx + c 
      - ax^2 - bx - c 
      + ax^2 + bx + c
      - ax^2 - bx - c
      + ax^2 + bx + c
  \end{equation*}
  
  \[
    h(x) = \int_a^b \frac{c}{d} x\,\mathrm{d}x
  \]
  
  \[
    i(x) = \int_a^b \frac{c}{d} x\,\mathrm{d}x
      - \int_a^b \frac{c}{d} x\,\mathrm{d}x
      + \int_a^b \frac{c}{d} x\,\mathrm{d}x
      - \int_a^b \frac{c}{d} x\,\mathrm{d}x
      + \int_a^b \frac{c}{d} x\,\mathrm{d}x
      - \int_a^b \frac{c}{d} x\,\mathrm{d}x
      + \int_a^b \frac{c}{d} x\,\mathrm{d}x
  \]
\end{frame}

\end{document}