Numbering side-by-side equations or inline equations

Question

I am trying to produce a two-column table of math equations, where each cell contains its own left-justified, numbered equation.

I tried using \begin{equation} \end{equation} inside the tabular environment, or inside a description list with multicols, and I can get the numbering, but not the left-justification.

I thought about using inline math mode in the table, but how do I get those equations to be numbered? Is there a little \numberthisequation command I can include in the ( inline-math ) commands?

I suppose, I could use two \minipages side by side, but I was hoping for something a little more straightforward.

Thanks!

Answer 1

This is a little workaround to get what you need:

\documentclass[12pt,letterpaper]{article}

\usepackage{amsmath}

\begin{document}

\begin{tabular}{p{8cm}p{8cm}}

{\begin{align}
&\alpha = \beta + \gamma \\
&c = 20x^2 + 5x - 10
\end{align}}
&
{\begin{align}
&x_f = x_0 + v_0t \\
&\mu = 10 * \epsilon
\end{align} }

\end{tabular}

\end{document}

The key concepts with this example are:

• You use tabular with columns defined by p{dim}.
• The tabular has only one row.
• For every cell of the tabular, you have an array of equations (align), whose equations are defined at the right of the &, so they get aligned to the left.
• Very important trick: to compile, you have to enclose every align environment inside {}, so that the & doesn't collide with those of the tabular.

One flaw this approach has: as every align environment is independent from the others, if one of the equations has more height, then they will look misaligned vertically. Try writing the

\frac{at^2}{2}

to the right of the third equation.

Answer 2

To left-align equations globally, use the fleqn option when loading amsmath. To left-align equations for only part of the document, you could load the nccmath package and use its fleqn environment. But then you'd still have the equations in actual equation environments, which creates vertical spacing problems.

It seems pretty simple to make your own inline equation tags, though, so try this:

\documentclass{minimal}

\newcommand{\teqtag}{\hfill\stepcounter{equation}(\theequation)}

\begin{document}
\begin{tabular}{p{2 in}@{\hspace{0.25 in}}p{2 in}}
  $\alpha=\beta+\gamma$\teqtag & $c=20x^2+5x-10$\teqtag   \\
  $\alpha=\frac{10x}{\int y\,dx}+\gamma$\teqtag & $c=20x^2+5x-10$\teqtag\\
  $x_f=x_0+v_0 t$\teqtag       & $\mu=10*\epsilon$\teqtag
\end{tabular}
\end{document}

Or to number the equations column-first (and put the tag on the left while we're at it):

\documentclass{minimal}

\newcommand{\lteqtag}{\stepcounter{lequation}(\thelequation)\ }
\newcommand{\rteqtag}{\stepcounter{requation}(\therequation)\ }
\newenvironment{spliteqs}%
  {\newcounter{lequation}%
  \newcounter{requation}%
  \setcounter{lequation}{\value{equation}}%
  \setcounter{requation}{\value{equation}}%
  \addtocounter{requation}{3}}% number of left-column equations
  {\setcounter{equation}{\value{requation}}}

\begin{document}
\begin{spliteqs}
\begin{tabular}{p{2 in}@{\hspace{0.25 in}}p{2 in}}
  \lteqtag$\alpha=\beta+\gamma$ & \rteqtag$c=20x^2+5x-10$   \\
  \lteqtag$\alpha=\frac{10x}{\int y\,dx}+\gamma$\ & \rteqtag$c=20x^2+5x-10$\\
  \lteqtag$x_f=x_0+v_0 t$       & \rteqtag$\mu=10*\epsilon$
\end{tabular}
\end{spliteqs}
\end{document}

Answer 3

Hmmm I'm not sure if I understand your question... does this meet your needs?

\documentclass{article}
\usepackage{multicol}
\begin{document}

\begin{multicols}{2}
\begin{enumerate}
\item $a+b$
\item $c+d$ 
\item $e+f$
\columnbreak
\item $1+2$
\item $3+4$
\item $5+6$
\end{enumerate}
\end{multicols}

\end{document}

Here is what this looks like: