Defining a command for amsmath's align environment

Question

I'd like to define a shorthand command for \begin{align*} and \end{align*}. When I write

\newcommand{\ba}{\begin{align*}}

it works fine. But when I write

\newcommand{\ea}{\end{align*}}

LaTeX complains. It looks like it's interpreting it as part of the environment and is not happy with that. Anyone know how to fix this?

This seems the sort of thing you should have a shortcut for in your editor, rather than in LaTeX itself. — ShreevatsaR, Apr 21 '10 at 14:27

score 18 · Answer 1 · answered Apr 19 '10 at 06:02

18

An alternative solution -- this is the code in the custom document class I use for everything:

\newcommand{\eq}[1]{\begin{align*}#1\end{align*}}

Usage:

\eq{
  x^2 + 9 &= 0
}

(Obviously, change the command name to suit your preference.)

answered Apr 19 '10 at 06:02

Etaoin

600

Thanks for the help! I defined the \eq command, and it's working well. – Apr 30 '10 at 06:01
This is a great idea, thank you. What does the [1] signify? – Eric Auld Sep 26 '13 at 15:52
It's the number of arguments your new \eq command will require. See http://en.wikibooks.org/wiki/LaTeX/Macros for more information. – Etaoin Sep 28 '13 at 00:03

score 6 · Answer 2 · edited Jul 14 '17 at 13:45

A little testing shows that this appears to be fairly specific to the "align" environment from amsmath. For example,

\documentclass{article}

\usepackage{amsmath}

\newcommand{\bc}{\begin{center}}
\newcommand{\ec}{\end{center}}

\begin{document}

\bc
hello world
\ec

\end{document}

works fine. I'm not sure why align* doesn't work (it doesn't work without the star either); I suspect that the myriad expansions and aliases surrounding the align environment do something a little more complicated than a "traditional" LaTeX environment. However, I have found something that might just achieve the same objective for you:

\documentclass{article}

\usepackage{amsmath}

\newcommand{\ba}{\[\begin{aligned}}
\newcommand{\ea}{\end{aligned}\]}

\begin{document}

\ba
x^2 &= y^2 \\
z^2 &= t^2
\ea

\end{document}

Hope that helps!

score 1 · Answer 3 · edited Mar 09 '11 at 13:23

1

It seems to me that it's a bug.

\newcommand{\ba}{\begin{align}} 
\newcommand{\ea}{\end{align}}
\ba
x=1
\ea

LaTeX complains about align not being closed.

edited Mar 09 '11 at 13:23

Hendrik Vogt

37,935

answered Nov 18 '10 at 13:36

7

This is not a bug, but indeed unexpected behaviour of align. It's explained over at tex.stackexchange.com – Hendrik Vogt Nov 18 '10 at 16:21

Defining a command for amsmath's align environment

3 Answers3

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