amsmathequations
I've looked through the search but I couldn't find what I specifically want.
I have the following
\begin{equation}
\begin{split}
Very long equation
\end{split}
\end{equation}
Now, I have half a page left where I want to place that equation, but it is a little bit longer. The result is that LaTeX places the formula on the next page. Is there a way so that LaTeX automatically splits the equation over the two pages?
Add this in the preamble after loading amsmath
\allowdisplaybreaks
I suggest you use a split environment, which in contrast to multline may be used a subenvironment of equation. You need to specify an alignment point on each line with & and separate lines with \\. In this case the first line should be move left relative to the others and the package mathtools provides a convenient command for this:
\documentclass{article}
\usepackage{mathtools}
\begin{document}
\begin{equation}
\label{wave kinematic}
\begin{split}
\MoveEqLeft
\frac{\partial N(\sigma;\lambda;\theta;t)}{\partial t}
+ \frac{\partial C_{g,\lambda}N(\sigma;\lambda;\theta;t)}
{\partial \lambda} \\
&+ \cos\phi^{-1} \cdot
\frac{\partial C_{f,\phi}N(\sigma;\lambda;\theta;t)}{\partial
\phi} \\
&+ \frac{\partial C_{f,\theta}N(\sigma;\lambda;\theta;t)}{\partial
\theta}
+ \frac{\partial C_{f,\sigma}N(\sigma;\lambda;\theta;t)}{\partial
\sigma}
= \frac{S(\sigma;\theta;\lambda;\varphi;t)}{\sigma}
\end{split}
\end{equation}
\end{document}
I have split across three lines for clarity. If you wanted to just split in two parts, then multlined (notice the extra d) from the mathtools package would be a simpler solution:
\documentclass{article}
\usepackage{mathtools}
\begin{document}
\begin{equation}
\label{wave kinematic}
\begin{multlined}
\frac{\partial N(\sigma;\lambda;\theta;t)}{\partial t}
+ \frac{\partial C_{g,\lambda}N(\sigma;\lambda;\theta;t)}
{\partial \lambda}
+ \cos\phi^{-1} \cdot
\frac{\partial C_{f,\phi}N(\sigma;\lambda;\theta;t)}{\partial
\phi} \\
+ \frac{\partial C_{f,\theta}N(\sigma;\lambda;\theta;t)}{\partial
\theta}
+ \frac{\partial C_{f,\sigma}N(\sigma;\lambda;\theta;t)}{\partial
\sigma}
= \frac{S(\sigma;\theta;\lambda;\varphi;t)}{\sigma}
\end{multlined}
\end{equation}
\end{document}
All the above works with elsarticle class in your updated question. E.g. the first version becomes:
\documentclass[authoryear,preprint,review,12pt]{elsarticle}
\usepackage{mathtools}
\begin{document}
\begin{equation}
\label{wave kinematic}
\begin{split}
\MoveEqLeft
\frac{\partial N(\sigma;\lambda;\theta;t)}{\partial t}
+ \frac{\partial C_{g,\lambda}N(\sigma;\lambda;\theta;t)}
{\partial \lambda} \\
&+ \cos\phi^{-1} \cdot
\frac{\partial C_{f,\phi}N(\sigma;\lambda;\theta;t)}{\partial
\phi} \\
&+ \frac{\partial C_{f,\theta}N(\sigma;\lambda;\theta;t)}{\partial
\theta}
+ \frac{\partial C_{f,\sigma}N(\sigma;\lambda;\theta;t)}{\partial
\sigma}
= \frac{S(\sigma;\theta;\lambda;\varphi;t)}{\sigma}
\end{split}
\end{equation}
\end{document}
Best Answer
Not if you use
split. Section 3.9 of the amsmath package documentation says thatThe same section explains how to get the effect you need, using a different environment such as
alignormultline.