28

Consider the following example:

\documentclass{article}
\usepackage{amsmath,amssymb}
\begin{document}
    \begin{align}
    \prod a+bm      && \text{is a square in} && \mathbb{R}\\
    \prod a+b\theta && \text{is a square in} && \mathbb{R}[\theta]
    \end{align}

    \begin{eqnarray}
    \prod a+bm      & \text{is a square in} & \mathbb{R}\\
    \prod a+b\theta & \text{is a square in} & \mathbb{R}[\theta]
    \end{eqnarray}
\end{document}

enter image description here

The amount of white spce used by eqnarray is exactly what I want, whereas align adds a (in my opinion) freakishly large amount of white space. So I could just stick with eqnarray, but I've read that I should always (under any circumstances) refrain from using it.

So my question is, how do I make my equation look nice using align?

2
  • 2
    Why do you use two ampersands in the align environment and not just one?
    – malin
    Jul 27, 2013 at 13:31
  • @malin Because if I use only one, then everything looks very messy.
    – Phil-ZXX
    Jul 27, 2013 at 13:39

2 Answers 2

31

You could use the alignat environment, which is similar to align.

\documentclass[11pt]{article}
\usepackage[T1]{fontenc}
\usepackage{mathtools}
\usepackage{amssymb}

\begin{document}
  \begin{alignat}{2}
    \prod a+bm      &\quad \text{is a square in} &&\quad\mathbb{R}\\
    \prod a+b\theta &\quad \text{is a square in} &&\quad\mathbb{R}[\theta]
  \end{alignat}
\end{document}

In the »Math mode« document you can find more about advanced math typesetting.


enter image description here


Update:

As requested the same example but with all columns left aligned.

\documentclass[11pt]{article}
\usepackage[T1]{fontenc}
\usepackage{mathtools}
\usepackage{amssymb}

\begin{document}
  \begin{alignat}{3}
    &\prod a+bm      &&\quad \text{is a square in} &&\quad\mathbb{R}\\
    &\prod a+b\theta &&\quad \text{is a square in} &&\quad\mathbb{R}[\theta]
  \end{alignat}
\end{document}

enter image description here

3
  • Great, just one more question: Is it possible to have the two products, i.e. the capital PIs, right underneath each other (just like the two Rs are right underneath each other)?
    – Phil-ZXX
    Jul 27, 2013 at 13:36
  • @Tom: I have edited my answer accordingly. Jul 27, 2013 at 14:09
  • Is it possible to have center-aligned equations with alignat, as in the original question? Or only flushed left?
    – Dr_Zaszuś
    May 11, 2015 at 13:22
7
\documentclass{article}
\usepackage{amsmath, amssymb}
\begin{document}
\begin{align}                                                                      
  \prod a+bm &\phantom{=} \text{is a square in}\quad \mathbb{R}\\                  
  \prod a+b\theta &\phantom{=} \text{is a square in}\quad \mathbb{R}[\theta]       
\end{align}
\end{document}

enter image description here


Flush left as requested:

\documentclass{article}
\usepackage{amsmath}
\usepackage{amssymb}
\makeatletter
\newenvironment{lflalign}{%                                                         
  \def\align@preamble{%                                                             
    &\strut@                                                                        
    \setboxz@h{\@lign$\m@th\displaystyle{####}$}%                                   
    \ifmeasuring@\savefieldlength@\fi                                               
    \set@field                                                                      
    \hfil                                                                           
    \tabskip\z@skip                                                                 
    &\setboxz@h{\@lign$\m@th\displaystyle{{}####}$}%                                
    \ifmeasuring@\savefieldlength@\fi                                               
    \set@field                                                                      
    \hfil                                                                           
    \tabskip\alignsep@                                                              
  }                                                                                 
  \flalign}
{\endflalign}
\makeatother
\begin{document}
\begin{align}                                                                       
  \prod a+bm & \phantom{=}\text{is a square in}\quad \mathbb{R}\\                   
  \prod a+b\theta & \phantom{=}\text{is a square in}\quad \mathbb{R}[\theta]        
\end{align}
\begin{lflalign}
  \prod a+bm & \phantom{=}\text{is a square in}\quad \mathbb{R}\\
  \prod a+b\theta & \phantom{=}\text{is a square in}\quad \mathbb{R}[\theta]
\end{lflalign}
\end{document}

enter image description here

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