How can I write multiple lines in a subscript?

Question

Is there a way to force a line break inside a math mode text?

My example:

\[
  \underbrace{....}_\text{Some long text that should be multiline}
\]

Trying

\text{Some long text that\\ should be multiline}

Didn't do the trick.

Answer 1

You can use the \substack command, from the amsmath package, just like \text.

\[
  \underbrace{...}_{\substack{\text{Some long text that} \\ \text{should be multiline}}}
\]

The output:

Answer 2

• \substack, mentioned by Carsten, probably fits best to your \underbrace because of the centered alignment.

• subarray is similar but offers customizable alignment:

Example:

\[
 \underbrace{....}_{\begin{subarray}{l}\text{Some  long text that}\\
    \text{should be multiline}\end{subarray}}
\]

• \parbox also works in math mode. You could use a font size command inside.

Answer 3

Another possibility:

\[
 \underbrace{some equation}_{\text{Some long text that}\atop\text{should be multilined}}
\]

Answer 4

\documentclass[11pt]{article}
\usepackage{amsmath}

\newcommand\myText[1]{\text{\scriptsize\tabular[t]{@{}l@{}}#1\endtabular}}

\begin{document}

\[
  \underbrace{....}_\myText{Some long text that\\ should be multiline}
\]

\end{document}

Answer 5

A simple \parbox with a certain width should also do.

\documentclass[11pt]{article}
\usepackage{mathtools}   % loads »amsmath«

\begin{document}
  \[
    \underbrace{ax^3+bx^2+cx+d}_{\text{\parbox{10em}{Some text that should be multi-lined}}}
  \]
\end{document}

Answer 6

One more, for a very long text:

\documentclass{article}
\usepackage{lipsum}
\newlength{\mysum}
\settowidth{\mysum}{$1+2+3+4+5+6+7+8+9$}
\begin{document}
\begin{equation}
\underbrace{1+2+3+4+5+6+7+8+9}_{
\begin{minipage}{\mysum}\lipsum[2]\end{minipage}} 
\end{equation}
\end{document}