How to insert a long equation in whole page of two column format?

Question

I have an equation like this:

\begin{flalign}&I(pair_1,pair_2)=\nonumber\\
    &\begin{cases} 
        0 & if\:\begin{cases}
        \max\left(r\left(pair_1^{rx}\right),r\left(pair_2^{tx}\right)\right)\leq
        d(pair_1^{rx},pair_2^{tx})  \\ \& \\
        \max\left(r\left(pair_1^{tx}\right),r\left(pair_2^{rx}\right)\right)\leq
        d(pair_1^{tx},pair_2^{rx}) \end{cases}\\ 1 & otherwise
    \end{cases}\nonumber\\
\end{flalign}

I Want to show this equation in whole of two column page. Indeed avoid to put equation in only one column.

Solution

My first suggestion is that you use multicols environment by multicol package. For example, given your preamble:

\documentclass{doublecol-new}
%\usepackage{natbib,stfloats}
%\usepackage{mathrsfs}
%\usepackage{graphicx}
%\usepackage[tight,footnotesize]{subfigure}
%\usepackage{algorithmic}
%\usepackage{algorithm}
%\usepackage{tabularx}
\usepackage{amsmath}
\usepackage{multicol,lipsum}

\begin{document}
\begin{multicols}{2}
    \lipsum[1]
\end{multicols}

\begin{multicols}{1}
\begin{flalign}&I(pair_1,pair_2)=%\nonumber\\
&\begin{cases} 
0 & if\:\begin{cases}
\max\left(r\left(pair_1^{rx}\right),r\left(pair_2^{tx}\right)\right)\leq
d(pair_1^{rx},pair_2^{tx})  \\ \& \\
\max\left(r\left(pair_1^{tx}\right),r\left(pair_2^{rx}\right)\right)\leq
d(pair_1^{tx},pair_2^{rx}) \end{cases}\\ 1 & otherwise
\end{cases}\nonumber\\
\end{flalign}
\end{multicols}

\begin{multicols}{2}
    \lipsum[2]
\end{multicols}

\end{document}

This would give you the following output:

Also, a bit better looking:

\begin{multicols}{1}
    \begin{equation}
        I(pair_1,pair_2)=
        \begin{cases}
            0 & \text{if }
            \begin{cases}
                \max\left(r\left(pair_1^{rx}\right),r\left(pair_2^{tx}\right)\right)\leq d(pair_1^{rx},pair_2^{tx}) \\
                \& \\
                \max\left(r\left(pair_1^{tx}\right),r\left(pair_2^{rx}\right)\right)\leq d(pair_1^{tx},pair_2^{rx})
            \end{cases}\\
            1 & \text{otherwise}
        \end{cases}
    \end{equation}
\end{multicols}

Comments

[Hosein Aqajani]

this is the template that I have used: inderscience.com/www/download/latex-double-column.zip that used \documentclass{doublecol-new} also I have these packages: \usepackage{natbib,stfloats}, \usepackage{mathrsfs}, \usepackage{graphicx}, \usepackage[tight,footnotesize]{subfigure}, \usepackage{algorithmic}, \usepackage{algorithm}, \usepackage{tabularx}, \usepackage{amsmath}

[MattAllegro]

Let us know if this fits your requirements and always remember: MWE ;)

[alper]

This does not work if the equation is on the right side column

[MattAllegro]

@alper hi! here all the math is in single-column environment; text before it is in two columns above, text after it is in two columns below. This way it only makes sense if the equation follows text above in column n. 2