Use the following commands to change the font size in maths mode [1,2]:

`{displaystyle }`

- size for equations in display mode
`{textstyle }`

- size for equations in text mode; this will make the equation font size the same as the surrounding text
`{scriptstyle }`

- size for first level of sub- and superscripts
`{scriptscriptstyle }`

- size for subsequent sub- and superscripts

## Example

The font size of the equation $latex f\left(x\right)=x$ can be changed to fit with the surrounding text, or it can have a superscript in a smaller font with a superscript in an even smaller font.

```
\documentclass[a4paper,12pt]{article}
\begin{document}
\huge
This function $\displaystyle f\left(x\right)=y$ is the same \texttt{\char`\\huge} size as its surrounding text.
\small
This function $\textstyle f\left(x\right)=y$ is the same \texttt{\char`\\small} size as its surrounding text.
\normalsize
This function $f_{\scriptstyle i}\left(x\right)=y$ is \texttt{\char`\\normalsize} and contains \texttt{\char`\\scriptsize} text ($i$).
\large
This function $f_{\scriptstyle i_{\scriptscriptstyle j}}\left(x\right)=y$ is \texttt{\char`\\large}-sized and contains \texttt{\char`\\scriptsize} text ($i$) and \texttt{\char`\\scriptscriptsize} text ($j$).
\end{document}
```

## References

- Roberts, Andrew, 2011, Getting to grips with LaTeX: mathematics – part 2
- WikiBooks, 2020, LaTeX/Advanced Mathematics