Can one break stackrel text into multiple lines?

Question

I'm writing something up where I want to be explicit about some elementary operations I'm performing. I have an arrow between matrices with some text above the arrow showing what I'm doing. The text above the arrow is quite long, is it possible to cause a line break of some sort in stackrel?

My code is the following:

\stackrel{R2:= R2-2R1,\ R3:= R3+2R1}{\longrightarrow}

Could you show how you intend to use it? Perhaps even including some mock-up of the expected output. — Werner, Jan 31 '14 at 04:27

score 7 · Accepted Answer · answered Jan 31 '14 at 11:15

\substack or subarray are your friends.

I suggest two commands, one for centered alignment of the elementary operation denotations, one for left alignment, that you might prefer.

\documentclass{article}
\usepackage{amsmath}

\newcommand{\elem}[1]{% elementary operations
  \xrightarrow{\substack{#1}}%
}

\newcommand{\lelem}[1]{% elementary operations (left alignment)
  \xrightarrow{\begin{subarray}{l}#1\end{subarray}}%
}

\begin{document}

\[
\elem{R2:= R2-2R1,\\ R3:= R3+2R1}\quad
\lelem{R2:= R2-2R1,\\ R3:= R3+2R1}
\]

\end{document}

enter image description here

There's no need to have multiple lines: \elem{R2:=R2-2R1} would work seamlessly.

score 4 · Answer 2 · 2014-01-31T22:34:59.173

4

What is wrong with substack?

\documentclass{article}
\usepackage{amsmath}
\begin{document}
  $\stackrel{\substack{R2:= R2-2R1,\\ R3:= R3+2R1}}{\longrightarrow}$
\end{document}

enter image description here

edited Jan 31 '14 at 22:34

answered Jan 31 '14 at 02:39

The first is of course wrong. – egreg Jan 31 '14 at 11:18
The vertical alignment will be completely wrong. – egreg Jan 31 '14 at 22:19

score 3 · Answer 3 · answered Jan 31 '14 at 02:33

Perhaps a combination of \overset and \shortstack?

\documentclass{article}
\usepackage{amsmath}

\begin{document}

\[
\overset{\shortstack{$\scriptstyle R2:= R2-2R1$,\\ $\scriptstyle R3:= R3+2R1$}}{\longrightarrow}\quad
\overset{\shortstack[l]{$\scriptstyle R2:= R2-2R1$,\\ $\scriptstyle R3:= R3+2R1$}}{\longrightarrow}
 \]

\end{document}

enter image description here

The optional argument for \shortstack allows you to control the alignment.

Can one break stackrel text into multiple lines?

3 Answers3