# I am trying to span lengthy equations across a two-column page in Overleaf. When I use the \begin{strip}, a digit is displayed in b/w two equations

    \documentclass[twocolumn]{article}
\usepackage{graphicx}
\usepackage{cuted}
\usepackage{amsmath}

\begin{document}
\maketitle

\section{Introduction}
\subsection{Equations}
In this section, we will explore how to compose lengthy equations intended to be formatted within a single column on a two-column paper.\\
\newline

\begin{strip}
$$A = Q^{u+1} - \frac{Q^{u+1}}{r \cdot c} \left(1 - \frac{r}{2}\right)- \frac{-Q^{u} \left(1 - r \cdot c\right)}{r \cdot c} \left(1 - \frac{r}{2}\right) - Q_{\text{rand}}^{u} \left(\frac{r}{2} - 1\right)$$
\end{strip}

\begin{strip}
\label{eq13}$$A = Q^{u+1} - \frac{Q^{u+1}}{r \cdot c} \left(1 - \frac{r}{2}\right)- \frac{-Q^{u} \left(1 - r \cdot c\right)}{r \cdot c} \left(1 - \frac{r}{2}\right) - Q_{\text{rand}}^{u} \left(\frac{r}{2} - 1\right)$$
\end{strip}

\begin{strip}
$$\label{eq13} A = Q^{u+1} - \frac{Q^{u+1}}{r \cdot c} \left(1 - \frac{r}{2}\right)- \frac{-Q^{u} \left(1 - r \cdot c\right)}{r \cdot c} \left(1 - \frac{r}{2}\right) - Q_{\text{rand}}^{u} \left(\frac{r}{2} - 1\right)$$
\end{strip}

\end{document}

• I get no pdf output at all from that test file Commented Oct 1, 2023 at 13:49
• you need x (or anything) before \end{document} to get output (which then does show the 5) Commented Oct 1, 2023 at 13:51
• I have edited, please check now. @DavidCarlisle Commented Oct 1, 2023 at 13:56

As @Zarko has already suggested in a comment, do consider placing the three separate equations in a suitably-chosen align or gather environment.

\documentclass[twocolumn]{article}
\usepackage{cuted,amsmath,lipsum}

\begin{document}

\section{Introduction}
\subsection{Equations}
\lipsum[1][1-9] % filler text

\begin{strip}
\begin{align}
A &= Q^{u+1} - \frac{Q^{u+1}}{r \cdot c} \bigl(1 - \tfrac{r}{2}\bigr)
- \frac{-Q^{u} (1 - r \cdot c)}{r \cdot c} \bigl(1 - \tfrac{r}{2}\bigr)
- Q_{\textrm{rand}}^{u} \bigl(\tfrac{r}{2} - 1\bigr)
\\
A &= Q^{u+1} - \frac{Q^{u+1}}{r \cdot c} \bigl(1 - \tfrac{r}{2}\bigr)
- \frac{-Q^{u} (1 - r \cdot c)}{r \cdot c} \bigl(1 - \tfrac{r}{2}\bigr)
- Q_{\textrm{rand}}^{u} \bigl(\tfrac{r}{2} - 1\bigr)
\label{eq23} \\
A &= Q^{u+1} - \frac{Q^{u+1}}{r \cdot c} \bigl(1 - \tfrac{r}{2}\bigr)
- \frac{-Q^{u} (1 - r \cdot c)}{r \cdot c} \bigl(1 - \tfrac{r}{2}\bigr)
- Q_{\textrm{rand}}^{u} \bigl(\tfrac{r}{2} - 1\bigr)
\label{eq33}
\end{align}
\end{strip}

\null % insert an invisible marker

\end{document}

• this is what the OP should do but doesn't actually answer the more interesting question of where the heck the 5 comes from if you use adjacent strip. I spent a few minutes with \tracingall earlier (without success:-) Commented Oct 1, 2023 at 16:23

Alright, I found the answer. In above case we add all three equations within one command of \strip.

\begin{strip}

A = Q^{u+1} - \frac{Q^{u+1}}{r \cdot c} \left(1 - \frac{r}{2}\right)- \frac{-Q^{u} \left(1 - r \cdot c\right)}{r \cdot c} \left(1 - \frac{r}{2}\right) - Q_{\text{rand}}^{u} \left(\frac{r}{2} - 1\right)

\label{eq13}
A = Q^{u+1} - \frac{Q^{u+1}}{r \cdot c} \left(1 - \frac{r}{2}\right)- \frac{-Q^{u} \left(1 - r \cdot c\right)}{r \cdot c} \left(1 - \frac{r}{2}\right) - Q_{\text{rand}}^{u} \left(\frac{r}{2} - 1\right)

$$\label{eq13} A = Q^{u+1} - \frac{Q^{u+1}}{r \cdot c} \left(1 - \frac{r}{2}\right)- \frac{-Q^{u} \left(1 - r \cdot c\right)}{r \cdot c} \left(1 - \frac{r}{2}\right) - Q_{\text{rand}}^{u} \left(\frac{r}{2} - 1\right)$$

\end{strip}

• It will far better to merge your equation in gather math environment ... Commented Oct 1, 2023 at 14:17
• Tell me more about it. :) Commented Oct 1, 2023 at 14:19
• The first equation is missing an directive.
– Mico
Commented Oct 1, 2023 at 15:14
• @Mico Yes, it's typo. Commented Oct 2, 2023 at 5:35