How best to present long equations in two-column papers?
When I have had occasion to deal with obnoxiously large equations, I find that there are four strategies that do well for me. In order of readability, they are:
- Shrink the font: if you are allowed (any many venues do allow this), you can usually shrink the font on an equation a few points without affecting readability.
- Map separable terms of the equation to new variables, which can be given their own independent definition lines. This can really help readability in a complex equation as well.
--- The line of desperation ---
- Break the equation across two lines: this works up to about 1.6 lines worth of smaller-font equation. When combined with adjusting font size, you can often adjust where the break occurs to make it look reasonable.
- Move the equations to a full-width figure, where you can play all of the same games.
I suggest you check chapter 3.3.4 in the book Mathematics into Type published by the American Mathematical Society (AMS).
The book sets up specific rules for breaking the equations and also how to align these after breaking. The rules are too complex to be reproduced or duplicated well here so anyone interested should download the book using the link above for reference.