There are three issues that I would like to fix which are probably interlinked, but don't know how (have tried a couple of things):
1) Force the equation numbering of equation 3.7 to move to the right-hand side of the the lower equation (underneath the updownarrow, so it looks like the numbering of equation 3.8.
2) Avoid compressing the size of the lower equation
3) Avoid italic font of equation 3.8
This is my code:
\documentclass[12pt,twoside]{book}
\usepackage{amssymb}
\usepackage{amsthm}
\usepackage{amsmath}
\begin{document}
\begin{equation}
\frac{c_r(6\sigma+3)+4\sigma^2(\sigma-2P_c+1)-2P_c+1}{(2\sigma+1)^2} = 0 \\
\center\Updownarrow \\
P_c^* = \frac{4\sigma^2+4\sigma+1+4\sigma^3+6c_r\sigma+3c_r}{2(1+4\sigma)}\center
\label{3.7}
\end{equation}
\vspace{-3cm}
The original paper produces the following result:
\begin{equation}
P_c^* = \frac{4\sigma^2+4\sigma+1}{2(1+4\sigma)}
\label{3.8}
\end{equation}
\end{document}
Best Answer
You cannot break lines in
equation
. Use agathered
environment within equation. The label will be typeset between the equation lines, unless you loadamsmath
with thetbtags
option. If you want the label to appear on the last line, you can use thegather
environment, and\notag
on the first two lines: