Long equation spanning two-columns that occurs in right column

Question

I am trying to achieve the formatting of Eq. 29 shown in the figure below. Specifically:

1. this is a long equation that occurs in the right column of a two-column document

2. the equation is typeset to span both columns

3. the text in the left column before the equation continues BELOW the equation

I have tried the following strategies suggested on TeX.SE and other sites, and none of them produce the desired result. I include an image of the result to show why each is unsatisfactory for my application.

1. Using the strip environment from the cuted package: the text of the equation overlaps the text in the left-column (specifically, it overlaps a footnote)

and in other examples I have seen of this (below image is annotated from How to create the long equations in two columns paper) the text flows from left column to right above the equation and then left to right below the equation, which is not the desired flow I am after.

2. Placing the equation in a figure* environment: this causes the equation to float so it doesn't appear where it is discussed (note that Eq. 26 floats to the next page and therefore shows up after Eq. 27)

3. Using a minipage: to make this appear in the right location I have to use a kludge and insert it earlier in the document, which makes the equation numbering incorrect (I imagine I could add insult to injury by fiddling with the equation counter back and forth, but I was hoping for a solution that didn't require two wrong turns to make a right), it also overlaps the text in the right column.

4. Using the multicol package: all of the examples I have seen for this approach (e.g. https://stackoverflow.com/a/33022911/1181402) show the text flows from the left-column to the right column above the equation and then restart in the left column below the equation, which is not the desired text flow. Moreover, when I tried to use it, it also had the undesired side effect of transforming the single-column foot-notes span two columns.

Any suggestions for achieving the desired formatting shown in the first image?

Answer 1

A hallmark of fine typography is that it makes the material "look good" without drawing undue attention to itself. I can think of two analogies involving people. First, consider a recital by a famous singer (opera star?) that's accompanied by a talented pianist. If anybody remembers the work of the pianist a few days after the event, then it's almost certainly because the pianist managed to mess up badly at some point during the evening. Second, consider the work of a wedding photographer at some fancy wedding. If people remember the photographer, it's likely because he/she messed up badly. Don't believe me? YouTube has hundreds (thousands?) of "funny" postings of weddings in which the photographer messed up one way or another...

Creating a long/wide equation that spans both columns of a two-column document pretty much flies in the face of everything that fine (math) typography stands for. Just because LaTeX happens to provide the tools that let you create a long/wide equation that spans both columns in no way implies that you should create an object that shouts out loud "Look at me, here I am! I'm damn good-looking! Really! Keep looking at me! Ignore all the stuff above and below me! I'm so much more important!" Trust me, you do not want your paper to be remembered by readers as "Oh, that quaint paper with a couple of super-wide equations. I can't really remember anything about the paper, other than the fact that it had a few super-wide equations." If nothing else, such papers tend not to get cited a lot...

For the use case at hand, it's actually straightforward to rearrange the material so that it can typeset via two stand-alone equations, each fitting nicely within the width of the column.

You're obviously free to choose a different symbol than Q...

\documentclass[twocolumn]{article} % or some other suitable document class
\usepackage[T1]{fontenc}
\usepackage{newtxtext,newtxmath} % or some other suitable font
\usepackage{lipsum} % filler text
\newcommand\q[1]{q^{}_{\! #1}} % handy shortcut macro

\begin{document}

\lipsum[1][1-3] % filler text

Put 
\begin{equation*}
\begin{aligned}
Q&= \q{A4}\q{C1}-\q{A1}\q{C4} + \q{A3}\q{C2}-\q{A2}\q{C3} \\
 &\quad+\q{B4}\q{D1}-\q{B1}\q{D4} + \q{B3}\q{D2}-\q{B2}\q{D3} \,. 
\end{aligned}
\end{equation*}
Then
\begin{equation}
\xi^{}_C=2\arctan\bigl(Q/(\q{A}\cdot\q{C}+\q{B}\cdot\q{D})\bigr)
+2\pi k
\end{equation}

\lipsum[2][2-4] % more filler text

\end{document}