\documentclass[12pt]{article}

\newcommand\etc{{\sl etc\/.}}
\newcommand\formul{formul{\ae}}

\newcommand\beq{\begin{equation}}
\newcommand\eeq{\end{equation}}
\newcommand\beqa{\begin{eqnarray}}
\newcommand\eeqa{\end{eqnarray}}

\newcommand\rv[1]{\mathbf r_{#1}}

\title{{\LaTeX} style manual}
\author{Sourendu Gupta\\TIFR, Mumbai, India}
\date{Version 1.01, August 29, 2009.\\
Version 1, July 20, 2009.}

\begin{document}
\maketitle

\section{How to read this manual}

If you are looking at the formatted output (pdf, ps, \etc) of this file,
then you should also simultaneously look at the {\TeX} source. Conversely,
if your are looking at the {\TeX} source, then you have to look at the
formatted version at the same time.

\section{Keeping track: version numbers}

Always insert the date and your name into the title material of the
document. Putting your name there makes you publicly responsible for the
contents. Putting the date keeps track of the version, in case there are
updates. Another important aspect of version control is to keep a numbered
series of files for every major revision step in the document development
process. This is version 1.01 of this manual.

\section{Mind your language}

Always use a spell-checker. The best time to do this is just before
you send the manuscript to someone else.

\section{Automate: use macros}
\label{sc.macros}

For symbols that you use often in a document, like the word ``{\formul}''
here, define a macro. A macro allows you to change a definition without
embarking on a search-and-destroy mission.

\section{On punctuation}

The {\TeX} document preparation system is intelligent enough to tweak
spacings before and after punctuation marks. The {\TeX}book suggests that
one have a space {\sl after\/} a punctuation mark, but not {\sl before\/}.
In other words , avoid that, but follow this.

\section{Fine points about font changes}

When moving from one {\sl font\/} to another, understand that there are
questions of spacing which need fine techniques like that shown in the
{\LaTeX} source file {\sl here\/}.

Be aware of the difference between {\sl slant\/} and {\it italics\/}.

Note that font in math text, like $mv^2/r$ is different from that outside:
m, v and r. So, be careful to use $m$, $v$ and $r$ instead.


\section{Mathematics}

\subsection{In-line {\formul}}

In-line {\formul} must be written in the form $a=(\tan u-u)/u$ and not in
the form $a=\frac{\tan u-u}u$. More complicated expressions should be displayed
as equations and not in-line {\formul}. Definitions which will be used later
should also be put into displayed equations. 

\subsection{Aesthetics of displayed equations}

Occasionally it is better to
collect two {\formul} together into one line of a displayed equation---
\beq
   \mathbf r_{ij} =\rv i-\rv j, \qquad{\rm and}\qquad
   \mathbf r_{k,ij} =\rv k -\frac12(\rv i+\rv j).
\label{rijrkij}\eeq
Eq.\ (\ref{rijrkij}) looks better than
\beqa
   \mathbf r_{ij} &=& \rv i-\rv j,\label{rij}\\
   \mathbf r_{k,ij} &=& \rv k -\frac12(\rv i+\rv j).
\label{rkij}\eeqa
The array eqs.\ (\ref{rij},\ref{rkij}) also demonstrates how to line up
equations. Such lining up looks better than the random results of using
two separate equations, as below,
\beqa
   \mathbf r_{ij} &=& \rv i-\rv j,
\label{rijp}\eeqa
\beqa
   \mathbf r_{k,ij} &=& \rv k -\frac12(\rv i+\rv j).
\label{rkijp}\eeqa

\subsection{Automate: use labels}

Another thing to note in these examples is that you should never write
equation numbers explicitly in the text; use a label for each equation
and refer to the label in the text. Failure to do this is the cause of
many wasted man-hours in search-and-destroy operations every time you
insert or delete an equation. Notice that the logic of using labels is
very similar to the logic of using macros (Section \ref{sc.macros}).

\end{document}
