The floating environments figure* and table* allow adding wide, single-column tables or figures in a two- or multicolumn document.
Here is an example.
Wide figure in a 3-column-document
The example makes use of the multicol package. For two columns, it is sufficient to use the documentclass-option twocolumn. The starred version of figure, figure*, and table, table* are floating environments. Therefore, LaTeX will place the figure only on the second page, rather than at the beginning of the document.
\documentclass[11pt]{article}
\usepackage{multicol, blindtext}
\begin{document}
\begin{multicols}{3}
\begin{figure*}[ht]
\centering
\rule{\linewidth}{3cm}
\caption{Wide single column figure in a twocolumn document.}
\end{figure*}
\Blindtext
\end{multicols}
\end{document}
It works exactly the same way for tables.
Wide table in a 2-column-document
\documentclass[twocolumn]{article}
\usepackage{blindtext}
\begin{document}
\begin{table*}[ht]
\caption{Wide single-column table in a twocolumn document.}
\centering
\begin{tabular}{p{0.25\linewidth}p{0.25\linewidth}p{0.25\linewidth}}
\hline
column 1 & column 2 & column 3\\
\hline
cell 1 & cell 2 & cell 3\\
cell 1 & cell 2 & cell 3\\
\hline
\end{tabular}
\end{table*}
\Blindtext\Blindtext
\end{document}
Side-by-side figures with subfig
It works exactly the same for side-by-side figures and tables (subfig package). See my post on that topic for more details. In this example, the dblfloatfix package is loaded. It “fixes” an issue with the floating environment and allows placing figures and tables at the bottom of a page.
\documentclass[twocolumn]{article}
\usepackage{blindtext, subfig}
\usepackage{dblfloatfix} % fix for bottom-placement of figure
\setlength{\columnseprule}{0.5pt}
\begin{document}
\begin{figure*}[hb]
\centering
\subfloat[][]{
\rule{0.45\linewidth}{3cm}
}
\subfloat[][]{
\rule{0.45\linewidth}{3cm}
}
\caption{Wide single column figure in a twocolumn document.}
\end{figure*}
\Blindtext\Blindtext
\end{document}
Additional notes
By default, figures and table will always be placed either at the top of a page or occupy a whole page. In the last example, we saw that it is possible to “fix” the float issue using the dblfloatfix package. However, there is no way to place the figure in the middle of the page, using the option [b].
Mixing “starred” and “non-starred” figures/tables is possible. For LaTeX to display the floats in the right order, load the fixltx2e package.
You can change the horizontal space between columns through:
\setlength{\columnsep}{2cm}
The following code adds a separation line between columns:
\setlength{\columnseprule}{0.5pt}