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### 5.2 \twocolumn

Synopses:

\twocolumn
\twocolumn[prelim one column text]


Start a new page and produce two-column output. If the document is given the class option twocolumn then this is the default (see Document class options). This command is fragile (see \protect).

If the optional prelim one column text argument is present, it is typeset in one-column mode before the two-column typesetting starts.

These parameters control typesetting in two-column output:

\columnsep

The distance between columns. The default is 35pt. Change it with a command such as \setlength{\columnsep}{40pt}. You must change it before the two column mode starts; in the preamble is a good place.

\columnseprule

The width of the rule between columns. The default is 0pt, meaning that there is no rule. Otherwise, the rule appears halfway between the two columns. Change it with a command such as \setlength{\columnseprule}{0.4pt}, before the two-column mode starts.

\columnwidth

The width of a single column. In one-column mode this is equal to \textwidth. In two-column mode by default LaTeX sets the width of each of the two columns, \columnwidth, to be half of \textwidth minus \columnsep.

In a two-column document, the starred environments table* and figure* are two columns wide, whereas the unstarred environments table and figure take up only one column (see figure and see table). LaTeX places starred floats at the top of a page. The following parameters control float behavior of two-column output.

\dbltopfraction

The maximum fraction at the top of a two-column page that may be occupied by two-column wide floats. The default is 0.7, meaning that the height of a table* or figure* environment must not exceed 0.7\textheight. If the height of your starred float environment exceeds this then you can take one of the following actions to prevent it from floating all the way to the back of the document:

• Use the [tp] location specifier to tell LaTeX to try to put the bulky float on a page by itself, as well as at the top of a page.
• Use the [t!] location specifier to override the effect of \dbltopfraction for this particular float.
• Increase the value of \dbltopfraction to a suitably large number, to avoid going to float pages so soon.

You can redefine it, as with \renewcommand{\dbltopfraction}{0.9}.

\dblfloatpagefraction

For a float page of two-column wide floats, this is the minimum fraction that must be occupied by floats, limiting the amount of blank space. LaTeX’s default is 0.5. Change it with \renewcommand.

\dblfloatsep

On a float page of two-column wide floats, this length is the distance between floats, at both the top and bottom of the page. The default is 12pt plus2pt minus2pt for a document set at 10pt or 11pt, and 14pt plus2pt minus4pt for a document set at 12pt.

\dbltextfloatsep

This length is the distance between a multi-column float at the top or bottom of a page and the main text. The default is 20pt plus2pt minus4pt.

\dbltopnumber

On a float page of two-column wide floats, this counter gives the maximum number of floats allowed at the top of the page. The LaTeX default is 2.

This example uses \twocolumn’s optional argument of to create a title that spans the two-column article:

\documentclass[twocolumn]{article}
\newcommand{\authormark}[1]{\textsuperscript{#1}}
\begin{document}
\twocolumn[{% inside this optional argument goes one-column text
\centering
\LARGE The Title \\[1.5em]
\large Author One\authormark{1},
Author Two\authormark{2},
Author Three\authormark{1} \\[1em]
\normalsize
\begin{tabular}{p{.2\textwidth}@{\hspace{2em}}p{.2\textwidth}}
\authormark{1}Department one  &\authormark{2}Department two \\
School one                   &School two
\end{tabular}\\[3em] % space below title part
}]

Two column text here.