# Where can I find “aligned” environment documentation?

Where can I find "aligned" environment documentation? I tried on the web and in this site but I've not been able to find it.

• In the documentation of amsmath, more precisely all these environments are documented in amsldoc.pdf. – Bernard Aug 25 '17 at 9:11
• in amsmath documentation. then en.wikibooks.org/wiki/LaTeX/Advanced_Mathematics – Zarko Aug 25 '17 at 9:11
• in most tex distributions you can just issue the command texdoc amsmath – David Carlisle Aug 25 '17 at 9:13
• @GabrieleNicolardi how is Mico blaiming your question? We legitimately would like to know what people searched for when their search failed to find, so we can work on improving search results. A lot of people forget to start their google search with latex, when they search LaTeX related stuff online, then, yes, you often fail since Google does not know the context. – daleif Aug 25 '17 at 10:06
• It is mentioned in the manual, on page 8: "Like the array environment, these -ed variants also take an optional [t] or [b] argument to specify vertical positioning." – Torbjørn T. Aug 25 '17 at 10:32

## 2 Answers

The aligned environment is from the amsmath package, and as such the documentation of amsmath is the first place to look. As David says, most users will have the documentation of the packages installed with their TeX distribution, so you can execute

texdoc amsmath


in a terminal/command prompt to open amsldoc.pdf.

The description of aligned (and gathered, alignedat) is found in section 3.7 Alignment building blocks, which start on the bottom of page 7. On the middle of page 8, the optional arguments to these environments are described:

Like the array environment, these -ed variants also take an optional [t] or [b] argument to specify vertical positioning.

A quick example demonstrating the difference:

\documentclass{article}
\usepackage{amsmath}
\begin{document}
Text \begin{aligned} a \\ b \\ c \end{aligned} text
\begin{aligned}[b] a \\ b \\ c \end{aligned} text
\begin{aligned}[t] a \\ b \\ c \end{aligned} text.
\end{document}


You can find some information here: Mathmode.pdf, more precisely at chapter 25 (page 46). But watch out, there is an obsolescence warning at CTAN:

The au­thor con­sid­ers this pack­age now as be­ing too old and af­flicted with too many ty­po­graph­i­cal bugs. That’s why it has been clas­si­fied as “ob­so­lete”, at least for the time be­ing.