% \iffalse The license starting on line four applies to this file
%<*batchfile>
{\obeylines\obeyspaces \gdef\thepreamble{

Copyright 2014 by Benjamin Tatlock

This work may be distributed and/or modified under the conditions of the
LaTeX Project Public License, either version 1.3 of this license or (at your
option) any later version. The latest version of this license is in
  http://www.latex-project.org/lppl.txt
and version 1.3 or later is part of all distributions of LaTeX version
2005/12/01 or later.

This work has the LPPL maintenance status `maintained'.

The Current Maintainer of this work is Benjamin Tatlock.

This work consists of the file bropd.dtx and the derived files bropd.sty and
bropd.pdf.
}}
\begingroup
\input docstrip
\keepsilent
\expandafter\preamble\thepreamble\endpreamble
\askforoverwritefalse
\generate{\file{bropd.sty}{\from{bropd.dtx}{}}}
\endgroup
\documentclass{ltxdoc}
\usepackage{bropd,color,ifpdf}
\DoNotIndex{\def}
\EnableCrossrefs
\CodelineIndex
\RecordChanges
\GetFileInfo{bropd.sty}
\title{The \textsf{bropd} package\thanks{This documentation corresponds to
\textsf{bropd}~v\fileversion, dated \filedate.}}
\def\auth{Benjamin Tatlock}
\author{\auth\thanks{\texttt{\kern2.5em\textcolor{white}
{\char101\char109\char97\char105\char108}\kern-5em\auth\kern-4em\char46\kern
3.5em\char64\textcolor{white}{bropd}\kern-1em\char108\kern-1em\char105\ 
\kern-2em\char109\char97\kern1em\char46\textcolor{white}
{\char111\char114\char103}\kern-2em\ com}}}
\begin{document}
\maketitle
\begin{abstract}
The \textsf{bropd} package simplifies the process of writing differential
operators and brackets in \LaTeX. The commands facilitate the easy manipulation
of equations involving brackets and allow partial differentials to be expressed
in alternate forms.
\end{abstract}
\section{Introduction}
The \textsf{bropd} package introduces a bracket command that automatically
selects parentheses, square brackets or braces as appropriate based on the
number of brackets. As such, brackets can be freely added and removed without
alterations to the rest of an equation. Commands for typing ordinary and partial
differentials are also created, with two optional concise forms for partial
derivatives. Equations can therefore be written in a standard form and their
style altered globally at a later date.
\section{Usage}
This section outlines the use of the three commands provided by the
\textsf{bropd} package.
\subsection{Brackets}
The bracket command replaces \verb|\left(| and \verb|\right)| with the single
command, \verb|\br| to produce brackets in a math environment. The input
\verb|\br{x}| produces\[\br{x}.\]When nested, the type of bracket is determined
automatically, for example, \verb|r=\br{\br{x-a}^2+\br{y-b}^2}^{\frac{1}{2}}|
results in\[r=\br{\br{x-a}^2+\br{y-b}^2}^{\frac{1}{2}}.\]
\subsection{Differential operators}
\subsubsection{Ordinary differential}
The \verb|\od| command produces ordinary differentials, such as \verb|\od{y}{x}|
which is displayed as\[\od{y}{x}.\]The order of the differential can be
specified as an optional argument, illustrated here with the command
\verb|\od[2]{u}{x}=-\omega^2u| which results in\[\od[2]{u}{x}=-\omega^2u.\]When
using \verb|\od| with a sans-serif font, the package should be loaded with the
optional argument \verb|sans|.
\subsubsection{Partial differential}The command \verb|\pd| follows the same form
as \verb|\od|, but instead produces partial differentials. By default,
\verb|\pd{u}{t}=6u\pd{u}{x}-\pd[3]{u}{x}|
produces\[\pd{u}{t}=6u\pd{u}{x}-\pd[3]{u}{x}.\]Loading the package with the
option \verb|pdshort| results in an alternative format for partial
differentials:\[u_t=6uu_x-u_{xxx}\]If the optional argument is not a positive
integer, the default form is reverted to, as with \verb|\pd[n]xy|:\[\pd[n]xy\]A
second alternative form is produced when the option \verb|pdalt| is
specified:\[\partial_tu=6u\partial_xu-\partial_{xxx}u\]The syntax for partial
differentials is extended to allow higher order terms such
as\[\pd{u}{x,x,t}\]to be easily typeset with \verb|\pd{u}{x,x,t}|. When applying
a partial derivative to a longer term, the first argument can be left blank and
the longer string written as an additional argument, as demonstrated by
\verb|\pd{}{z}{x+y}| which results in\[\pd{}{z}{x+y}.\]To prevent brackets from
being placed after a partial differential with an empty numerator, use
\verb|!| for the first argument, for example, \verb|\pd{!}{x}|:\[\pd{!}{x}\]
\subsection{Further examples}
Combining the commands provided by this package allows more complex terms to be
written concisely. The \verb|\br| allows equations with multiple brackets to be
constructed and manipulated quickly and easily. An example of this is
\verb|\br{x-y}\br{Q-\frac12\br{P+\br{x-1}\br{\br{a+b}\br{u+c}-\od st}}}|, which
results in\[\br{x-y}\br{Q-\frac12\br{P+\br{x-1}\br{\br{A+B}\br{u+c}-\od st}}}.\]
The form of the partial differentials written with the \verb|\pd| command can
be changed at any time. \verb|\pd Et+\sum_{i=1}^3\pd{}{x_i}{\br{E+p}u_i}|
produces\[\pd Et+\sum_{i=1}^3\pd{}{x_i}{\br{E+p}u_i}\]by default. With
\verb|pdshort|, the same input instead
creates\[E_t+\sum_{i=1}^3\br{\br{E+p}u_i}_{x_i},\]while with \verb|pdalt| the
output is\[\partial_tE+\sum_{i=1}^3\partial_{x_i}\br{\br{E+p}u_i}.\]
\StopEventually{\typeout{**************************************************}
\typeout{*}
\typeout{* To finish the installation, you have to move the}
\typeout{* following file into a directory searched by TeX:}
\typeout{*}
\typeout{* \space\space bropd.sty}
\typeout{*}
\typeout{* Documentation is in bropd.\ifpdf pdf\else dvi\fi.}
\typeout{*}
\typeout{**************************************************}\end{document}}
\clearpage
\DocInput{bropd.dtx}
\clearpage
\PrintChanges
\Finale
%</batchfile>
% \fi
% \section{Implementation}
% Announce the name, package version and \LaTeXe\ requirement
% \changes{v1.0}{2012/11/04}{Initial version}
%    \begin{macrocode}
\NeedsTeXFormat{LaTeX2e}
\ProvidesPackage{bropd}
[2014/10/14 1.2 automated typing of brackets and differential operators]
%    \end{macrocode}
% Initiate conditionals and counters
%    \begin{macrocode}
\newif\if@bropd@a\newif\if@bropd@b\newif\if@bropd@s\newif\if@bropd@u
\newcounter{@bropd@c}\newcounter{@bropd@d}
\newcounter{@bropd@e}\newcounter{@bropd@f}
%    \end{macrocode}
% Provide optional arguments for alternative form partial differential and
% sans-serif fonts
%    \begin{macrocode}
\DeclareOption{pdshort}{\@bropd@atrue\@bropd@ufalse}
\DeclareOption{pdalt}{\@bropd@atrue\@bropd@utrue}
\DeclareOption{sans}{\@bropd@strue}\ProcessOptions
%    \end{macrocode}
% Define character for \verb|\pd| with empty numerator and no brackets following
%    \begin{macrocode}
\def\@bropd@t{!}
%    \end{macrocode}
% \begin{macro}{\@bropd@g}
% Internal command for default partial differential form
%    \begin{macrocode}
\def\@bropd@g#1#2#3#4{\def\@bropd@h{#1}
%    \end{macrocode}
% Create numerator
%    \begin{macrocode}
\ifx\@bropd@o\@bropd@t\let\@bropd@o\empty\fi
%    \end{macrocode}
% Reset counters
%    \begin{macrocode}
\ifx\@bropd@h\empty
\setcounter{@bropd@c}0\setcounter{@bropd@d}1
\let\@bropd@h\empty
%    \end{macrocode}
% Determine order of partial derivative and display as power of partial if
% greater than one
%    \begin{macrocode}
\@for\@bropd@i:=#3\do{\stepcounter{@bropd@c}}
\frac{#4\ifnum\value{@bropd@c}>1
^{\arabic{@bropd@c}}\fi\@bropd@o}
%    \end{macrocode}
% Cycle through each term for the denominator. If a term is the same as the
% previous, add to counter, otherwise print along with counter value
%    \begin{macrocode}
{\@for\@bropd@i:=#3\do{
\ifx\@bropd@i\@bropd@h
\stepcounter{@bropd@d}
\else
\@bropd@h
\ifnum\value{@bropd@d}>1
^{\arabic{@bropd@d}}
\fi
#4\setcounter{@bropd@d}1
\fi
\let\@bropd@h\@bropd@i}
\@bropd@h
\ifnum\value{@bropd@d}>1
^{\arabic{@bropd@d}}\fi}
\else
%    \end{macrocode}
% If optional argument provided, display partial differential to stated order
% \changes{v1.1}{2012/11/08}{Fixed higher order differentials with denominators
% containing commands}
%    \begin{macrocode}
\frac{#4^{#1}\@bropd@o}{#4\noexpand#3^{#1}}
\fi}
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\@bropd@j}
% Internal command for brackets. Evaluate terms within brackets to determine the
% highest bracket level
% \changes{v\fileversion}\filedate{Changed \cs{bgroup} to \cs{begingroup} and
% \cs{egroup} to \cs{endgroup} to remove erroneous introduction of space before
% and after brackets}
%    \begin{macrocode}
\def\@bropd@j#1{\setcounter{@bropd@f}0
\begingroup\renewcommand{\br}[1]{\stepcounter{@bropd@e}##1
\ifnum\value{@bropd@e}>\value{@bropd@f}
\setcounter{@bropd@f}{\value{@bropd@e}}
\fi
\addtocounter{@bropd@e}{-1}}\sbox0{$#1$}\endgroup
\loop
\ifnum\value{@bropd@f}>2
\addtocounter{@bropd@f}{-3}
\repeat
%    \end{macrocode}
% Detemine bracket type for current level
%    \begin{macrocode}
\ifnum\value{@bropd@f}>0
\ifnum\value{@bropd@f}>1
\def\@bropd@k{\left\lbrace#1\right\rbrace}
\else
\def\@bropd@k{\left[#1\right]}
\fi
\else
\def\@bropd@k{\left(#1\right)}
\fi}
\if@bropd@a
\let\@bropd@l\empty
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\br}
% External command for brackets
%    \begin{macrocode}
\newcommand\br[1]{\let\@bropd@m\@bropd@l
\@bropd@j{\let\@bropd@l\empty#1\let\@bropd@l\@bropd@m}
\ifx\@bropd@l\empty
\def\@bropd@n{\@bropd@k}
\else
\let\@bropd@m\@bropd@l
\def\@bropd@n{\@bropd@k_{\@bropd@m}}
\fi
\let\@bropd@l\empty
\@bropd@n}
\if@bropd@u
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\@bropd@q}
% Internal command for first alternative partial differential command
% \changes{v1.1}{2012/11/08}{Added second alternative form for partial
% differentials}
%    \begin{macrocode}
\def\@bropd@q#1#2#3{\def\@bropd@h{#1}
\ifx\@bropd@h\empty
\@bropd@bfalse
\else
%    \end{macrocode}
% Default partial differential if character provided as optional argument
% \changes{v1.1}{2012/11/08}{Allowed partial differential with empty numerator
% without need for bracket command after}
%    \begin{macrocode}
\if!\ifnum9<1#1!\else_\fi
\@bropd@bfalse
\else
\@bropd@btrue
\fi
\fi
\ifx\@bropd@o\@bropd@t
\@bropd@btrue\let\@bropd@o\empty
\fi
\if@bropd@b\@bropd@g{#1}\@bropd@o{\noexpand#3}\partial
\else
%    \end{macrocode}
% Construct alternate form partial differential
%    \begin{macrocode}
\partial_{\ifx\@bropd@h\empty
\@for\@bropd@i:=#3\do\@bropd@i\else\setcounter{@bropd@c}0
\loop
\ifnum\value{@bropd@c}<#1
#3\stepcounter{@bropd@c}
\repeat
\fi}
\@bropd@o
\fi}
\else
%    \end{macrocode}
% Internal command for second alternative partial differential command
%    \begin{macrocode}
\def\@bropd@q#1#2#3{\def\@bropd@h{#1}
\ifx\@bropd@h\empty
\@bropd@bfalse
\else
%    \end{macrocode}
% Default partial differential if character provided as optional argument
%    \begin{macrocode}
\if!\ifnum9<1#1!\else_\fi
\@bropd@bfalse
\else
\@bropd@btrue
\fi
\fi
\ifx\@bropd@o\@bropd@t
\@bropd@btrue\let\@bropd@o\empty
\fi
\if@bropd@b\@bropd@g{#1}\@bropd@o{\noexpand#3}\partial
\else
%    \end{macrocode}
% Construct alternate form partial differential
%    \begin{macrocode}
\def\@bropd@p{\ifx\@bropd@h\empty
\@for\@bropd@i:=#3\do\@bropd@i\else\setcounter{@bropd@c}0
\loop
\ifnum\value{@bropd@c}<#1
#3\stepcounter{@bropd@c}
\repeat
\fi}
\ifx\@bropd@o\empty
\let\@bropd@l\@bropd@p\else{\@bropd@o}{_{\@bropd@p}}\fi\fi}
\fi
\else
%    \end{macrocode}
% Internal command for default partial differentials
%    \begin{macrocode}
\def\@bropd@q#1#2#3{\@bropd@g{#1}{#2}{\noexpand#3}\partial}
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\br}
% External command for brackets
%    \begin{macrocode}
\newcommand\br[1]{\@bropd@j{#1}\@bropd@k}
\fi
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\pd}
% \changes{v1.1}{2012/11/08}{Brackets automatically added after empty numerator}
%    \begin{macrocode}
\newcommand\pd[3][]{\def\@bropd@o{#2}
\ifx\@bropd@o\empty
\let\@bropd@v\br
\else
\let\@bropd@v\empty
\fi
\@bropd@q{#1}{#2}{#3}\@bropd@v}
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\@bropd@r}
% Format ordinary differential based on font type
%    \begin{macrocode}
\if@bropd@s
\def\@bropd@r{\mathsf d}
\else
\def\@bropd@r{\mathrm d}
\fi
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\od}
% External command for ordinary differentials
%    \begin{macrocode}
\newcommand\od[3][]{\def\@bropd@h{#1}
\frac{\@bropd@r\ifx\@bropd@h\empty\else^{#1}\fi#2}
{\@bropd@r#3\ifx\@bropd@h\empty\else^{#1}\fi}}
\endinput
%    \end{macrocode}
% \end{macro}
% \endinput