How to end \large?

Question

I have put \large before an equation, as I want it to be bigger than the default size. However, the font in the following paragraph has been enlarged too.

Is there a command I can put in between the end of the equation and the beginning of the new paragraph of text, so that the font returns to the normal size for the text?

Answer 1

You don't want to issue \large before an equation. Consider the example

\documentclass{article}
\usepackage{amsmath}

\usepackage{lipsum}

\begin{document}

\lipsum[1][1-6]

\lipsum[1][1-6]\large
\begin{equation}
a+b+c
\end{equation}\normalsize
\lipsum[1][1-6]

\end{document}

Can you see the problem? \large acts also on the text before the equation: not on the type size, but on the baseline distance.

Using a blank line before \large doesn't really help

You get too much space above the equation and it also might go at the top of the next page.

If you want that the equation number is large, which is reasonable, you can do as follows:

\documentclass{article}
\usepackage{amsmath}

\usepackage{lipsum}

\newenvironment{largeequation}
 {$$\begin{minipage}{\displaywidth}\large
  \abovedisplayshortskip=0pt \belowdisplayshortskip=0pt
  \noindent\begin{equation}}
 {\end{equation}\end{minipage}$$\ignorespacesafterend}

\begin{document}

\lipsum[1][1-6]

\lipsum[1][1-6]
\begin{largeequation}
a+b+c
\end{largeequation}
\lipsum[1][1-6]

\end{document}

Note. Yes, I used $$ because I do know what it's for. 😉😀 But it's used in the definition of the environment, not in the document body, where it must never be used.

Answer 2

The \large macro sets the font size and this setting is done locally. Typically, you can do this in a TeX group. When TeX group ends then this setting is removed.

The display math is processed in TeX group, so you can do the font re-sizing at the start of the display math. For examle, in OpTeX it looks like this:

\lorem[2]
$$
  \typosize[15/]  a^2 + b^2 = c^2  \eqno (1)
$$
\lorem[3]

\bye