Change the size of a math symbol

Question

How can I get something like in the figure, where G in the middle is larger than normal letters in math mode?

Answer 1

You can use the \mathlarger command from relsize. If you want to have a choice for the new size, you can use the \text{} command, change the text font size and insert a math formula inside:

\documentclass{article}
\usepackage{amsmath}
\usepackage{relsize}%


 \begin{document}

\[ F \longrightarrow \text{\Large$ G $}\longrightarrow H \]

\[ F \longrightarrow \mathlarger{G}\longrightarrow H \]

\end{document} 

Answer 2

The package relsize can help:

\documentclass{article}
\usepackage{amsmath}
\usepackage{relsize}

\begin{document}
\begin{center}
$F\to \text{\larger[2]$G$} \to H$
\\
$F\to \mathlarger{G} \to H$
\\
$F\to \mathlarger{\mathlarger{G}} \to H$
\end{center}
\begin{gather}
F\to \text{\larger[2]$G$} \to H
\\
F\to \mathlarger{G} \to H
\\
F\to \mathlarger{\mathlarger{G}} \to H
\end{gather}
\end{document}

The first three lines emulate inline math mode, centered for easier comparison, whereas the second group of three formulas emulate display math mode.

You can notice that a single \mathlarger doesn't change the size in inline math, so probably you want to go for

\mathlarger{\mathlarger{G}}

Of course, you want to make a new command for it:

\newcommand{\bigletter}[1]{\mathlarger{\mathlarger{#1}}}
\newcommand{\bigG}{\bigletter{G}}

This way you can delay the final choice to the last minute.

Answer 3

I'd say: you have to encapsulate the letter in the middle in a \mbox.

MWE:

\documentclass[12pt,a4paper,twoside]{scrartcl}
\usepackage[utf8]{luainputenc}
\begin{document}

\begin{equation}
  F \rightarrow \mbox{\Large$G$} \rightarrow H
\end{equation}

\end{document}

Result

Answer 4

In case that you need a non standard size (as those that you can obtain with commands like \text{\Large$G$}) a simple solution to obtain any size is a \scalebox:

\documentclass{article}
\usepackage{amsmath,graphicx}
\begin{document}
\( F \longrightarrow \text{\LARGE\ensuremath G} \longrightarrow H \)\par
\( F \longrightarrow \scalebox{1.9}{\ensuremath G} \longrightarrow H \)\par
\( F \longrightarrow \text{\huge\ensuremath G} \longrightarrow H \)
\end{document}