I have a very long equation

```
\begin{equation*}
\begin{aligned}
multiple line equation...
\end{aligned}
\end{equation}
```

But just using the above code causes the whole equation to start from a new page leaving behind a third of previous page empty.

Where should i put the \displaybreak command to ensure that the page breaks occurs conveniently in between the equation.

I tried using it in the following manner but it doesn't help.

```
\begingroup
\allowdisplaybreak
\begin{equation*}
\begin{aligned}
multiple line equation...
\end{aligned}
\end{equation}
\endgroup
```

## Best Answer

The point is that, aligned environment wraps its contents inside an unbreakable box. So, these commands (that is, both

`\displaybreak`

and`\allowdisplaybreaks`

) do not have any effect.This is true of

`split`

,`gathered`

and`alignedat`

environments too.So, to get the line break to work, you might consider using

`align*`

, as suggested by egreg.You might want to refer to

`amsldoc`

, towards the end of page 6 for these comments. I'd also like to draw your attention to the section 3 of this document for discussions regarding display math._{ By the way, please note that, you have s missing in \allowdisplaybreaks.}