last column of multicols has excessive whitespace

Question

The last column of a multicols has extra whitespace that is not needed (as visually the margin will do):

\begin{multicols}{3}
\begin{description}
\item[asdf] - fdasdf
\item[asdf] - fdasdf
\item[asdf] - fdasdf
\item[as42df] - fda432sdf
\item[as42df] - fda432sdf
\item[as42df] - fda432sdf
\item[59093] - 5324
\item[59093] - 5324
\item[59093] - 5324
\end{description}
\end{multicols}

The table will not look centered.

Basically I want to center the multicols visually (which means that the minimal bounding box (i.e., excluding whitespace) is centered).

Answer 1

I would suggest going with a more rigid structure then; something like a tabular would work fine:

\documentclass{article}
\usepackage{multicol}% http://ctan.org/pkg/multicol
\usepackage{showframe}% http://ctan.org/pkg/showframe
\begin{document}
\begin{multicols}{3}
  \begin{description}
    \item[asdf] - fdasdf
    \item[asdf] - fdasdf
    \item[asdf] - fdasdf
    \item[as42df] - fda432sdf
    \item[as42df] - fda432sdf
    \item[as42df] - fda432sdf
    \item[59093] - 5324
    \item[59093] - 5324
    \item[59093] - 5324
  \end{description}
\end{multicols}

\begin{center}
  \begin{tabular}{l@{\quad}l@{\quad}l}
    \textbf{asdf} - fdasdf & \textbf{as42df} - fda432sdf & \textbf{59093} - 5324 \\[.7\normalbaselineskip]
    \textbf{asdf} - fdasdf & \textbf{as42df} - fda432sdf & \textbf{59093} - 5324 \\[.7\normalbaselineskip]
    \textbf{asdf} - fdasdf & \textbf{as42df} - fda432sdf & \textbf{59093} - 5324
  \end{tabular}
\end{center}
\end{document}

You can fiddle around with the horizontal space between the columns (\quad in my MWE). Another option would be to use a paragraph-style p{<len>} column type, which would allow for using description. The vertical lines on the side are from the showframe package indicating the text block boundaries.

You don't mention the requirement to necessarily keep the description environment, nor being able to break across the page boundary.

---

Perhaps a less-attractive alternative would be to wrap multicols inside an adjustwidth environment (from changepage) to modify the left & right margin temporarily. Not sure how much problems this might cause down the road though:

\documentclass{article}
\usepackage{multicol}% http://ctan.org/pkg/multicol
\usepackage{showframe}% http://ctan.org/pkg/showframe
\usepackage{changepage}% http://ctan.org/pkg/changepage
\begin{document}
\begin{multicols}{3}
  \begin{description}
    \item[asdf] - fdasdf
    \item[asdf] - fdasdf
    \item[asdf] - fdasdf
    \item[as42df] - fda432sdf
    \item[as42df] - fda432sdf
    \item[as42df] - fda432sdf
    \item[59093] - 5324
    \item[59093] - 5324
    \item[59093] - 5324
  \end{description}
\end{multicols}

\begin{adjustwidth}{1cm}{1cm}
  \begin{multicols}{3}
    \begin{description}
      \item[asdf] - fdasdf
      \item[asdf] - fdasdf
      \item[asdf] - fdasdf
      \item[as42df] - fda432sdf
      \item[as42df] - fda432sdf
      \item[as42df] - fda432sdf
      \item[59093] - 5324
      \item[59093] - 5324
      \item[59093] - 5324
    \end{description}
  \end{multicols}
\end{adjustwidth}

\end{document}

Note that the margin adjustments do not take the environment contents into consideration. As such, disproportionate columns will cause a disproportionate layout and "centering adjustment."

Answer 2

The multicols environment will naturally center its columns with no excessive whitespace as you see. The reason you experiencing this problem is your use of a list. You will need to redefine your list environment. Here is a MWE employing the plain vanilla trivlist environment, showing that the problem disappears. The rest is just filler text.

\documentclass{article}
\usepackage{multicol,lipsum}
\begin{document}
\begin{multicols}{3}
\begin{trivlist}
\item [test] this is something
\item [test] this is something
\end{trivlist}
\lipsum
\end{multicols}
\end{document}

A package that you may find suitable is the multienum. Here is MWE using it with maths.

\documentclass{article}
\usepackage{multicol,lipsum}
\usepackage{multienum}
\renewcommand{\regularlisti}{\setcounter{multienumi}{0}%
  \renewcommand{\labelenumi}%
  {\addtocounter{multienumi}{1}\alph{multienumi})}}
\begin{document}
\begin{multienumerate}
\mitemxxx{\(x^2 + y^2 = 1\)}{\(a + b = c\)}{\(r-x = y+z\)}
\mitemxxx{\(f - y = z\)}{\(a - b = 2d\)}{\(r+x = 2y-3z\)}
\end{multienumerate}
\end{document}