% \iffalse
%
% mattens.dtx  Copyright (C) 2001 DNJ Els
%
% It may be distributed and/or modified under the
% conditions of the LaTeX Project Public License, either version 1.1
% 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 1.1 or later is part of all distributions of LaTeX
% version 1999/06/01 or later.
%
%<*driver>
\documentclass{ltxdoc}
\usepackage{amsmath}
\usepackage{color}

% Declare the following two saved boxes before
% the accents and bm packages are loaded

\newsavebox{\AccentBox}
\sbox{\AccentBox}{$\dot{\overline{f}}^a_b$}

\newcounter{cnt}
\newsavebox{\nested}
\newcommand*{\Sym}[1]{%
    \boldsymbol{{#1\addtocounter{cnt}{1}}}}
\sbox{\nested}{%
   $Q_\text{\leavevmode\rlap%
         {$\Sym{x}_i$}%
        ${\smash{\dot{\overrightarrow{\phantom{\Sym{x}}}}}%
          \vphantom{\overrightarrow{\Sym{x}^j}}}$}$}

\usepackage{array}
\usepackage{accents}
\usepackage{mattens}
\usepackage{bm}
\bmdefine{\bO}{\mathit{\Omega}}

\EnableCrossrefs
%\DisableCrossrefs      % Say \DisableCrossrefs if index is ready
\CodelineIndex
\RecordChanges         % Gather update information
%\OnlyDescription       % comment out for implementation details
\setlength\hfuzz{15pt} % dont make so many
\hbadness=7000         % over and under full box warnings
\DeclareMathAlphabet{\mathsfsl}{OT1}{cmss}{m}{sl}
\setlength{\parindent}{0pt}
\setlength{\parskip}{\medskipamount}
\begin{document}
   \DocInput{mattens.dtx}
\end{document}
%</driver>
%
% \fi
%
% \CheckSum{734}
%% \CharacterTable
%%  {Upper-case    \A\B\C\D\E\F\G\H\I\J\K\L\M\N\O\P\Q\R\S\T\U\V\W\X\Y\Z
%%   Lower-case    \a\b\c\d\e\f\g\h\i\j\k\l\m\n\o\p\q\r\s\t\u\v\w\x\y\z
%%   Digits        \0\1\2\3\4\5\6\7\8\9
%%   Exclamation   \!     Double quote  \"     Hash (number) \#
%%   Dollar        \$     Percent       \%     Ampersand     \&
%%   Acute accent  \'     Left paren    \(     Right paren   \)
%%   Asterisk      \*     Plus          \+     Comma         \,
%%   Minus         \-     Point         \.     Solidus       \/
%%   Colon         \:     Semicolon     \;     Less than     \<
%%   Equals        \=     Greater than  \>     Question mark \?
%%   Commercial at \@     Left bracket  \[     Backslash     \\
%%   Right bracket \]     Circumflex    \^     Underscore    \_
%%   Grave accent  \`     Left brace    \{     Vertical bar  \|
%%   Right brace   \}     Tilde         \~}
%%
%
% \DoNotIndex{\,, \@empty, \@gobble, \@ifnextchar, \@ifstar,
%             \@ifundefined}
% \DoNotIndex{\addtolength}
% \DoNotIndex{\begingroup, \boldsymbol, \box}
% \DoNotIndex{\copy, \csname, \CurrentOption}
% \DoNotIndex{\DeclareOption, \DeclareRobustCommand, \def, \dp}
% \DoNotIndex{\edef, \else, \endcsname, \endgroup, \ensuremath,
%             \expandafter}
% \DoNotIndex{\fi}
% \DoNotIndex{\global}
% \DoNotIndex{\hskip, \ht}
% \DoNotIndex{\ifdim}
% \DoNotIndex{\leavevmode, \left, \let, \lVert}
% \DoNotIndex{\m@th, \mathpalette, \mathsf, \mathstrut, \mskip}
% \DoNotIndex{\NeedsTeXFormat, \newbox, \newcommand, \newif, \newlength,
%             \newmuskip, \newsavebox, \null}
% \DoNotIndex{\overline}
% \DoNotIndex{\PackageError, \PackageWarning, \ProcessOptions, \protect,
%             \protected@xdef, \providecommand, \ProvidesPackage}
% \DoNotIndex{\relax, \renewcommand, \RequirePackage, \right, \rlap,
%             \rVert}
% \DoNotIndex{\sbox, \setbox, \setlength, \space, \string}
% \DoNotIndex{\the}
% \DoNotIndex{\underline, \usebox, \wd, \widetilde}
% \DoNotIndex{\z@}
%
% \changes{1.0}{2001 Dec 9}{Initial version}
%
%
% \GetFileInfo{mattens.sty}
%
% ^^A Some commands to format document %%%%%%%%%%%%%
%
% \newcommand*{\pkg}[1]{\textsf{#1}}
% \newcommand*{\opt}[1]{\textsf{#1}}
% \newcommand*{\MT}{\pkg{mattens}}
% \newcommand*{\Hass}{Hassenpflug}
%
% \newcommand*{\myemph}[1]{\textsl{#1}}
%
%  \newenvironment{Decl}^^A
%     {\par\small\addvspace{4.5ex plus 1ex}^^A
%      \vskip -\parskip
%      \noindent\hspace{\leftmargini}^^A
%      \begin{tabular}{|l|}\hline\ignorespaces}^^A
%     {\\\hline\end{tabular}\nobreak\par\nobreak
%      \vspace{2.3ex}\vskip -\parskip}
%
% \newenvironment{Indent}[1]{^^A
%    \begin{list}{}{^^A
%       \setlength{\topsep}{0pt}^^A
%       \setlength{\leftmargin}{#1}^^A
%       \setlength{\listparindent}{\parindent}^^A
%       \setlength{\itemindent}{\parindent}^^A
%       \setlength{\parsep}{\parskip}}^^A
%     \item[]
%   }{\end{list}}
%
% \newenvironment{sample}{^^A
%   \begin{quote}\small\begin{tabbing}^^A
%   \hskip12pc\=\kill}^^A
%   {\end{tabbing}\end{quote}}
%
% \newcommand*{\sphline}{^^A     horizontal table line with spaces
%    \noalign{\vskip3pt}^^A
%    \hline^^A
%    \noalign{\vskip3pt}}
%
% \newcommand{\dotr}[1]{\accentset{\phantom{r}{\displaystyle.}r}{#1}}
%
% \MakeShortVerb{\|}
%
% \title{The \MT\ package\thanks{This file has version number
%                               \fileversion, last revised
%                               \filedate.}}
% \author{Danie Els\\
%       \small Department of Mechanical Engineering\\
%       \small University of Stellenbosch, South Africa\\
%              e-mail: \texttt{dnjels@sun.ac.za}}
% \date{\filedate}
% \maketitle
%
% \begin{abstract}
% \setlength{\parskip}{\medskipamount}\setlength{\parindent}{0pt}
% \noindent This package contains the definitions to typeset the matrix
% tensor notation of \myemph{\Hass}\cite{Hass93a,Hass93b}. It consists of
% symbols such as \aS{e}_i, \bS[\dot]{x}^r, \bSb{E}^s_r, etc.  This
% notation was developed and refined by Dr.~\Hass{} over many years of
% teaching engineering, and as stated by him\cite{Hass93a}:
%
% \begin{quote}
% \slshape``It is designed particulary to distinguish between
% vectors and tensors and their representation as vectors and matrices
% in different coordinate systems. The main purpose of this notation
% is that it can be used in the teaching situation, therefore, it
% conveys all the information explicitly in the symbols, and it can be
% used in handwriting.''
% \end{quote}
%
% An appeal is made to the engineering and scientific community to
% adopt this notation, especially for the representation of common
% vectors and tensors such as forces, velocities, moments of inertia,
% etc., because of its consistency and ease of use.
%
% \slshape{\bfseries Keywords:} vector, matrix, tensor, notation.
% \end{abstract}
%
% \clearpage
% {\parskip0pt\tableofcontents}
%
% \clearpage
% \section{Introduction}
% \subsection{Background}
%
% A browse through journals and handbooks, in particular those
% concerned with dynamics, reveals an amazing array of private
% notations for vectors and tensors. Every author has his or her own
% notation, making it very difficult to comprehend what is going on
% in complex multi reference axes environments.
%
% \myemph{\Hass}\cite{Hass93a} identifies the following list of
% requirements for a good notation for tensor quantities and
% operations, to which his notation conforms:
%
% A notation must
% \begin{enumerate}
% \item be easily written by hand;
% \item distinguish between vector and scalar quantities;
% \item distinguish between (second order) tensors and vectors;
% \item distinguish between physical vectors and their
%       representation by vector arrays, and between physical
%       (second order) tensors and their representation by matrices;
% \item distinguish between row and column vectors;
% \item use the same symbol as name for the same vector or tensor in
%       either its physical sense or its representation by a vector
%       array or matrix in different coordinate axes;
% \item distinguish between matrix/vector representation of the same
%       vector/tensor in different coordinate axes;
% \item be equally valid in orthonormal and skew coordinate
%       axes;
% \item indicate all intended operations uniquely;
% \item be equally valid in all dimensions;
% \item be equally valid for algebraic vector/matrix algebra
%       which has no connection to any metric space;
% \item be applicable to differentials;
% \item allow for defaults to avoid repetitive elaborate symbols, i.e.,
%       not all the symbols need to be written down explicitly if it is
%       clear from the context.
% \item It must be well documented (own addition).
% \end{enumerate}
%
% The \MT\ package was developed to typeset the \Hass{} matrix
% tensor symbols in a consistent manner.
%
%
% \section{Usage of \MT\ package}
%
% The \MT\ package is loaded in the document preamble with:
% \begin{quote}
% \begin{tabbing}^^A
% \hskip14pc\=\kill^^A
% $~~~\vdots$\\
% \cmd{\usepackage}\oarg{options}|{mattens}| \>|% amsmath loaded internally|\\
% $~~~\vdots$\\
% \cmd{\usepackage}\marg{font packages}      \>|%|\\
% \cmd{\DeclareSymbolFont}...                \>|% All the font changes|\\
% \cmd{\SetSymbolFont}...                    \>|%|\\
% \cmd{\DeclareSymbolFontAlphabet}...        \>|%|\\
% $~~~\vdots$\\
% \cmd{\usepackage}|{bm}       %\boldsymbol redirected to call \bm|\\
% $~~~\vdots$
% \end{tabbing}
% \end{quote}
%
% When \MT\ is loaded, the \pkg{amsmath} package is loaded
% automatically, because it is needed for the redefined
% \cmd{\overrightarrow} and \cmd{\underrightarrow} commands,
% as well as the \cmd{\boldsymbol} command. It
% must be loaded before any font packages
% that redefine some of the \pkg{amsmath} symbols or commands.
%
% On the other hand, the preferred method for obtaining bold
% italic math symbols is the \cmd{\bm} command of the
% \pkg{bm} package\footnote{In the \pkg{amsmath} documentation,
% \AmS{} recommends the \cmd{\bm} command of the \pkg{bm} package
% instead of the \cmd{\boldsymbol} command for bold italic math
% symbols.}.
% The \pkg{bm} package must be loaded after all the font packages
% in order for it to recognize the bold math versions.
% The \pkg{bm} package reroutes the \cmd{\boldsymbol} command to point
% to \cmd{\bm}. If \cmd{\boldsymbol} is called after
% the \pkg{bm} package is loaded, it is equivalent to
% \cmd{\bm}.
% If the \pkg{bm} package is not loaded, \MT\ defaults to
% the \cmd{\boldsymbol} command.
%
% The \MT\ package by default sets bold italics symbols. This
% choice stems from the ISO standards for typesetting of vectors
% and tensors. The formatting of symbols then indicates the fact
% that it is a vector/tensor and the lines, arrows and sub- and
% superscripts indicate the specific type and reference axes.
%
% The following options are recognized by \MT:
%
% \begin{description}
% \item[\normalfont\opt{noformat} ---]  No symbol formatting is performed,
%      otherwise symbols are set by default in bold italics with the
%      \cmd{\boldsymbol} or \cmd{\bm} command.
%
%      It is important to note that the \Hass{} requirement of easily
%      written by hand is not fulfilled if the symbols are formatted
%      by anything else than normal math fonts.
%
% \item[\normalfont\opt{mathstrut} ---] A mathstrut is inserted
%      with the symbol to force all the lines and arrows to the same
%      height and depth. The default is no mathstrut.
% \end{description}
%
% \clearpage
% \section{List of \MT\ commands}
%
% \begin{table}[htbp]
% \caption{List of Matrix Tensor typing commands} \label{tab:1}
% \begin{minipage}{1.05\textwidth}
% \small
% \renewcommand{\footnoterule}{}
% \begin{tabular*}{\textwidth}{@{}>{\slshape}l l>{\itshape}r@{}>{\itshape}c@{}>{\itshape} l c@{}}
% \sphline \textbf{\slshape Type} &
% \textbf{\slshape Command}&
% \multicolumn{3}{c}{\textbf{\slshape Description}} &
% \textbf{\slshape Output}\\
% \sphline
% Physical column vector&
% \cmd{\aS}\oarg{accent}\marg{Symbol}\SpecialUsageIndex{aS}  &
% arrow--&Symbol&       &
% \aS{x}  \\[1.0ex]
%
% Physical row vector   &
% \cmd{\Sa}\oarg{accent}\marg{Symbol}\SpecialUsageIndex{Sa}  &
%        &Symbol&--arrow&
% \Sa{x}  \\[1.0ex]
%
% Column vector         &
% \cmd{\bS}\oarg{accent}\marg{Symbol}\SpecialUsageIndex{bS}  &
%    bar--&Symbol&       &
% \bS{x}  \\[1.0ex]
%
% Row vector            &
% \cmd{\Sb}\oarg{accent}\marg{Symbol}\SpecialUsageIndex{Sb}  &
%         &Symbol&--bar  &
% \Sb{x}  \\[1.0ex]
%
% Physical tensor       &
% \cmd{\aSa}\oarg{accent}\marg{Symbol}\SpecialUsageIndex{aSa}&
%  arrow--&Symbol&--arrow&
% \aSa{E}\\[1.0ex]
%
% Tensor (mixed base)   &
% \cmd{\aSb}\oarg{accent}\marg{Symbol}\SpecialUsageIndex{aSb}&
%  arrow--&Symbol&--bar  &
% \aSb{E}\\[1.0ex]
%
% Tensor (mixed base)   &
% \cmd{\bSa}\oarg{accent}\marg{Symbol}\SpecialUsageIndex{bSa}&
%    bar--&Symbol&--arrow&
% \bSa{E}\\[1.0ex]
%
% Tensor                &
% \cmd{\bSb}\oarg{accent}\marg{Symbol}\SpecialUsageIndex{bSb}&
%   bar--&Symbol&--bar  &
% \bSb{E}\\[1.0ex]
%
% Cross-product tensor\footnote{It is defined as the tensor
%    \bCSb{a}\ associated \protect\\ with the vector \bS{a}, where
%    $\bS{a}\times\bS{c}=\bCSb{a}\cdot\bS{c}$}
%                       &
% \cmd{\aCSa}\oarg{accent}\marg{Symbol}\SpecialUsageIndex{aCSa}&
% arrow--C&Symbol&--arrow&
% \aCSa{w} \\[1.0ex]
%
% Cross-product tensor  &
% \cmd{\bCSb}\oarg{accent}\marg{Symbol}\SpecialUsageIndex{bCSb}&
%   bar--C&Symbol&--bar  &
% \bCSb{w} \\[1.0ex]
%
% \sphline
% \end{tabular*}
% \end{minipage}
% \end{table}
%
% \subsection{General syntax}
%
% The general syntax of the \MT\ commands is
%
% \begin{Decl}
%       |\|$\alpha$|S|$\gamma$\oarg{accent}\marg{Symbol} ~~~~
%       |\|$\alpha$|CS|$\gamma$\oarg{accent}\marg{Symbol}\\[1ex]
%       |\|$\alpha$|S|$\gamma$\,|*|\oarg{accent}\marg{Symbol}~~~
%       |\|$\alpha$|CS|$\gamma$\,|*|\oarg{accent}\marg{Symbol}
% \end{Decl}
%
% with command names \cmd{\bS}, \cmd{\aS}, \cmd{\aSa}, \cmd{\aSb}, etc.
% See Tab.\:\ref{tab:1} for a full list of all the commands.  The
% ``starred'' form is used to set the
% symbol in normal math. This can be used for compound tensors or for
% pre-declared symbols (see \pkg{bm} documentation).
%
% An example of the usage is
% \begin{sample}
% \hskip4pc\=\hskip8pc\=\hskip2pc\=\kill^^A
% \cmd{\aS}|{e}|  \> \cmd{\aS*}|{e}|   \> \aS{e}  \> \aS*{e}\\[0.75ex]
% \cmd{\Sb}|{x}|  \> \cmd{\Sb*}|{x}|   \> \Sb{x}  \> \Sb*{x}\\[0.75ex]
% \cmd{\aCSa}|{z}|\> \cmd{\aCSa*}|{z}| \> \aCSa{z}\> \aCSa*{z}
% \end{sample}
%
% The optional argument \meta{accent} is intended for
% \LaTeX{} accent commands such as \cmd{\dot}, \cmd{\ddot}, etc., or
% their $\AmS$ equivalents, \cmd{\Dot}, \cmd{\Ddot}.
%
% \begin{sample}
% |\bS[\ddot]{x}| \> \bS[\ddot]{x}
% \end{sample}
%
% The \MT\ commands look ahead for sub- and superscripts
% in order to place them at the correct horizontal and vertical
% positions.
% \begin{sample}
% \cmd{\bS}|[|\cmd{\dot} |]{x}^s_i|  \> \bS[\dot]{x}^s_i\\[.75ex]
% \cmd{\bS}|[|\cmd{\ddot}|]{x}_i^s|  \> \bS[\ddot]{x}_i^s\\[.75ex]
% \cmd{\bSa}|{E}^k|         \> \bSa{E}^k\\[.75ex]
% \cmd{\aSb}|{E}_s|         \> \aSb{E}_s
% \end{sample}
%
% These commands, including the sub- and
% superscripts, can be used in text mode.
%
% \begin{sample}
% |Vector \bS{x}^s_i{} in text.| \>
%  Vector \bS{x}^s_i{} in text.
% \end{sample}
%
% The commands are also robust and can be used in moving commands
% such as footnotes\footnote{A vector \aS{e}_i\ in a footnote},
% headers, etc.
%
% \begin{sample}
% |\footnote{A vector \aS{e}_i{} in a footnote}|
% \end{sample}
%
% The symbols scale to the appropriate sizes if used in sub- and
% superscripts. For example, for an integration path parameterized
% by the vector $\bS{r}^s(\xi)$, the equation for a line integral
%
% \begin{verbatim}
%    \begin{equation*}
%       \oint\limits_{\bS{r}^s(\xi)}  \dotsi
%     \end{equation*}
% \end{verbatim}
% gives
% \[\oint\limits_{\bS{r}^s(\xi)} \dotsi\]
%
% \bigskip
%
% \clearpage
% \section{Symbol formatting commands}
% \subsection{Bold italic symbols}
%
% The symbol format can be set with the package options
%
% \begin{sample}
% \hskip14pc\=\kill
% |\usepackage{mattens}|             \>Uses |\boldsymbol| as default\\
% |\usepackage[noformat]{mattens}|   \>No symbol formatting
% \end{sample}
%
% or anywhere in the document with the command
%
% \begin{Decl}
%   \cmd{\SetSymbFont}\marg{font-command}^^A
%   \SpecialUsageIndex{\SetSymbFont}
% \end{Decl}
%
% The \pkg{bm} package reroutes the \cmd{\boldsymbol} command to point
% to \cmd{\bm}. If \cmd{\SetSymbFont}|{\boldsymbol}| is called after
% the \pkg{bm} package is loaded, it is equivalent to
% \cmd{\SetSymbFont}|{\bm}|.  Bold formatting of individual tensors
% can also be switched off with the use of the starred forms of the
% tensor commands.
%
% If the symbols are interpreted as tensors, then according to the ISO,
% it can be typeset in a slanted sans serif font (if you are fond
% of fonts).  For the Computer Modern fonts with an \texttt{OT1}
% encoding, you can put in the preamble
%
% \begin{quote}
% |\DeclareMathAlphabet{\mathsfsl}{OT1}{cmss}{m}{sl}|
% \end{quote}
%
% Examples of formats are
%
% \begin{sample}
% |\SetSymbFont{\bm}|       \>\SetSymbFont{\bm}\aSb{E}_s\\[1ex]
% |\SetSymbFont{\relax}|    \>\SetSymbFont{\relax}\aSb{E}_s\\[1ex]
% |\SetSymbFont{\mathsfsl}| \>\SetSymbFont{\mathsfsl}\aSb{E}_s
% \end{sample}
% \SetSymbFont{\bm}
%
% Only the first symbol (or group) in multi-symbol constructions is
% formatted. This can be used to obtain
%
% \begin{sample}
% |\bS{{}xy}| ~|\bS*{xy}| \> \bS{{}xy} ~ \bS*{xy}\\
% |\bS{xy}|   \> \bS{xy} \\
% |\bS{{xy}}| \> \bS{{xy}}
% \end{sample}
% or
% \begin{sample}
% |\bCSb*{\bS{x}+\bS{y}}| \> \bCSb*{\bS{x}+\bS{y}}\\[1ex]
% |\bSb{E_{313}}^s_r| \> \bSb{E_{313}}^s_r
% \end{sample}
%
% When a font does not have bold italic symbols and is properly
% configured, the |\bm| command
% constructs the symbols with the ``poor man's bold''
% method. This results in the loss of the subscript kerning.
% This is the case for the \pkg{mathptm}\ package for Times fonts.
% If bold italic symbols are needed for Times fonts, it is advisable
% to use the \pkg{txfonts} package or one of the commercial fonts.
%
%
% \subsection{Struts}
%
% A strut can be inserted inside the tensor construction to force
% all the lines to the same height. This can be given in the package
% options
%
% \begin{sample}
% \hskip14pc\=\kill
% |\usepackage{mattens}|             \>No strut as default \\
% |\usepackage[mathstrut]{mattens}|  \>Uses |\mathstrut|
% \end{sample}
%
% or anywhere in the document with the command
%
% \begin{Decl}
%    \SpecialUsageIndex{\SetSymbStrut}^^A
%    \cmd{\SetSymbStrut}\marg{strut}
% \end{Decl}
%
% For example
%
% \SetSymbStrut{\mathstrut}%
% \begin{sample}
% |\SetSymbStrut{\mathstrut}| \\
% |\bSb{E}|, |\bS{f}|, |\Sb{y}| \>\bSb{E}, \bS{x}, \Sb{y}
% \end{sample}
% \SetSymbStrut{\vphantom{E}}%
% \begin{sample}
% |\SetSymbStrut{\vphantom{E}}| \\
% |\bSb{E}|, |\bS{f}|, |\Sb{y}| \>\bSb{E}, \bS{x}, \Sb{y}
% \end{sample}
% \SetSymbStrut{\relax}
% \begin{sample}
% |\SetSymbStrut{\relax}| \\
% |\bSb{E}|, |\bS{f}|, |\Sb{y}| \>\bSb{E}, \bS{x}, \Sb{y}
% \end{sample}
%
% \subsection{Additional sub- and superscript spaces}
%
% The placing of the sub- and superscripts was fine-tuned for
% Computer Modern fonts. Other fonts may require the sub- and
% superscript to shift closer or further away from the lines and the
% symbols. Additional spaces can be inserted before the sub- and
% superscripts with the following commands:
%
% \begin{Decl}
%    \cmd{\SetArrowSkip}\marg{muskip length}\\
%    \cmd{\SetBarSkip}\marg{muskip length}\\
%    \cmd{\SetSymSuBSkip}\marg{muskip length}\\
%    \cmd{\SetSymSuPSkip}\marg{muskip length}
%    \SpecialUsageIndex{\SetArrowSkip}
%    \SpecialUsageIndex{\SetBarSkip}
%    \SpecialUsageIndex{\SetSymSuBSkip}
%    \SpecialUsageIndex{\SetSymSuPSkip}
% \end{Decl}
%
% The length units must be in math units (\myemph{mu}), where
% $18\,\mathit{mu}=1\,\mathit{em}$ (a little less than the
% width of the letter ``M'').
%
%
% \clearpage
% \section{Additional commands}
% \subsection{Saving equations}
%
% The \MT\ commands use a large number of calculations.
% When the same symbol is used repetitively throughout
% a document, a command
%
% \begin{Decl}
%   \SpecialUsageIndex{\DeclareSBox}
%   \cmd{\DeclareSBox}\marg{$\backslash$cmd}\marg{contents}
% \end{Decl}
%
% is provided that saves the \meta{contents} in a savebox
% |\MTbox@|\textit{cmd}. It then defines a command |\|\textit{cmd} that
% expands to |\usebox{\MTbox@|\textit{cmd}|}|.
%
% It is \myemph{very important} to remember that it is the fully
% expanded version of the \meta{contents} that is saved and not the macros.
% If |\|\textit{cmd} is used in a different environment the
% contents will retain the settings they were declared with. The
% saved boxes (and commands) are defined globally so that the contents
% of the box are not destroyed when a group is exited.
%
% \begin{sample}
% \hspace{17pc}\=\kill
% |{\large\DeclareSBox{\Le}{\bS{e}^s}}| \> {\large\DeclareSBox{\Le}{\bS{e}^s}}\\
% |{\small\DeclareSBox{\se}{\bS{e}^s}}| \> {\small\DeclareSBox{\se}{\bS{e}^s}}\\
% |Test \Le\ and \se\ here.|               \> {\normalsize Test \Le\ and \se\ here.}
% \end{sample}
%
% This command is also useful for saving other objects such as
% the graphics of logos that are used repetitively.
%
%
% \subsection{Helper commands}
%
% When matrices and tensors are typed, there are some commands that
% occur frequently and these are therefore included in the \MT\ package.
%
% \begin{Decl}
%   \SpecialUsageIndex{\SB}
%   \cmd{\SB}\marg{argument}
% \end{Decl}
%
% This command puts square brackets, \texttt{[...]},
% around its argument, and can be used in text mode. The square
% brackets are preferred for the first level delimiter to indicate
% that we are dealing with matrices.
%
% \begin{sample}
% |$\SB{\bSb{E}^s_r}^{-1}$| \> $\SB{\bSb{E}^s_r}^{-1}$ \\[.5ex]
% |$\SB{\bS{x}+\bS{y}\,}$|    \> $\SB{\bS{x}+\bS{y}\,}$
% \end{sample}
%
% \begin{Decl}
%   \SpecialUsageIndex{\norm}
%   \cmd{\norm}\marg{argument}
% \end{Decl}
%
% This command is provided if it does not already exist.
% \begin{sample}
% |$\norm{\aS{x}}=x$| \> $\norm{\aS{x}}=x$
% \end{sample}
%
% \begin{Decl}
%   \SpecialUsageIndex{\tdot}
%   \cmd{\tdot}
% \end{Decl}
%
% This command, which is shorthand for
% |\ensuremath{{\cdot}}|, sets a half-high dot to indicate matrix
% multiplication. It can be used in text mode.
%
% \begin{sample}
% |$\bS{x}^s = | \\
% |  \bSb{E}_r^s\tdot\bS{x}^r$| \>
% $\bS{x}^s =\bSb{E}_r^s\tdot\bS{x}^r$
% \end{sample}
%
% \begin{Decl}
%   \SpecialUsageIndex{\trnsp}
%   \cmd{\trnsp}
% \end{Decl}
%
% This command types the matrix transpose symbol ,\trnsp.
%
% \begin{sample}
% |$\SB{\bSb{E}^s_r}^\trnsp$| \> $\SB{\bSb{E}^s_r}^\trnsp$
% \end{sample}
%
%
% \section{Other programs, classes and packages}
%
% \begin{description}

% \item[\normalfont{\sffamily{\bfseries\scriptsize PDF}\LaTeX}]^^A
% --- The \MT\ package works fine, but some workarounds were necessary
%     when the \pkg{pdftex.def} driver is loaded with the \pkg{color},
%     \pkg{hyperref} or \pkg{graphics} packages. The main problem it
%     the \cmd{\usebox} command that functions differently from standard
%     \LaTeX{}. This is because \pkg{pdftex} does not implement a colour
%     stack such as in the \pkg{dvips} driver, but simulate it at \TeX{}
%     macro level.
% \\
%
% \item[\normalfont\pkg{hyperref} ---]
% When tensor symbols are set in chapter and section headers,
% \pkg{hyperref} crashes if the \cmd{\texorpdfstring} command is not used.
% \begin{sample}
%     |\section{A header with \texorpdfstring{\bS{x}^i_j}{xij}\ in it}| \\
% \end{sample}
%
% \item[\normalfont\pkg{color} ---]
% To change the colour of a symbol the \cmd{\color} command must
% be grouped two levels deep to survive all the expansions if the
% \pkg{bm} package is loaded.
% \begin{sample}
% |\aSb{{{\color{red}E}}}_i| \> \aSb{{{\color{red}E}}}_i \\
% \end{sample}
%
% \item[\normalfont\pkg{slide} ---]
% The Euler math fonts are definitely compulsory. The ratio of
% the sub- and superscript sizes to normal math font sizes is too
% big inside the \pkg{slide} class. For tensors such as \bS{x}^j_k,
% you may find that the sub- and superscripts overlap. Choose
% your script characters carefully. \\
%
% \item[\normalfont\pkg{eulervm} ---]
% The \Hass{} ideal of symbols that are easily written by hand
% is satisfied with the beautiful letters of the Euler fonts.
% This package is a must for presentation material, but \myemph{please
% do not use bold Euler symbols}, they just  do not look right! \\
%
% \item[\normalfont\pkg{accents} ---]
% For the creation of alternative accents the \MT\ package is fully
% compatible with the \pkg{accents}\ package.
% As an example of its usage, the equation in \myemph{\Hass}\cite{Hass93a},
% \S10.1, p.82
%
% \begin{minipage}{\textwidth}
% \begin{verbatim}
% \SetSymbFont{\relax}
% \newcommand{\dotr}[1]{\accentset{\phantom{r}{\displaystyle.}r}{#1}}
% \begin{equation*}
%    \text{apparent velocity} = \frac{\partial_r}{\mathrm{d}t} \aS{r}
%                             = \aS[\dotr]{r}
%                             = \aSb{E}_s \tdot \bS[\dotr]{r}^s
%                        \equiv \aS{v}_{\mathrm{app}}
%                             = \aS{v}_{\mathrm{rel}}
% \end{equation*}
% \end{verbatim}
% \end{minipage}
% which gives\SetSymbFont{\relax}
% \begin{equation*}
% \text{apparent velocity} =
% \frac{\partial_r}{\mathrm{d}t} \aS{r} =
% \aS[\dotr]{r} =
% \aSb{E}_s \tdot \bS[\dotr]{r}^s \equiv
% \aS{v}_{\mathrm{app}} =
% \aS{v}_{\mathrm{rel}}
% \end{equation*}
% \SetSymbStrut{\relax}\SetSymbFont{\bm} \\
%
% \item[\normalfont\pkg{bm} ---] The \pkg{bm} package is preferred for
% bold\-/\-heavy symbols in math mode. It can also be used to
% predeclare bold symbols for use with the starred form of the tensor
% commands, for example:
% \begin{sample}
%  |\bmdefine{\bO}{\mathit{\Omega}}| \\
%  |\bSb*{\bO_i}|  \>\qquad\qquad\qquad \bSb*{\bO_i}
% \end{sample}
%
% \end{description}
%
%
% \section{Typesetting the \Hass{} notation in \LaTeX}
% \subsection{Why?}
%
% The \Hass{} notation contains symbols such as, \aS{e}_i,
% \bS[\dot]{x}^{r}_{\alpha}, \bSa[\dot]{E}^s, etc. These symbols
% are quite common and variants thereof are found on many
% blackboards of engineering schools. Based on the reputation of
% \TeX{} it would seem trivial to typeset them, but to the contrary
% ...
% \SetSymbFont{\relax}
% \begin{sample}
% |\bS[\dot]{f}^a_b|        \> \bS[\dot]{f}^a_b ~~~(correct typesetting)\\[.75ex]
% |$\dot{\overline{f}}^a_b$| \> \usebox{\AccentBox}\\[.75ex]
% |$\dot{\overline{f}}{}^a_b$| \> $\dot{\overline{f}}{}^a_b$\\[.75ex]
% |$\dot{\overline{f}^a_b}$| \> $\dot{\overline{f}^a_b}$
% \end{sample}
% \SetSymbFont{\bm}
%
% When a subscript is inserted for slanted characters, e.g.,
% $f^a_b$, the subscript is kerned closer to the symbol.
% This subscript kerning as well as the superscript height is
% retained for math accents, e.g., $\dot{f}^a_b$. When
% the \cmd{\overline} or \cmd{\overrightarrow} commands are used together
% with math accents, the problems begin\footnote{If you are using
% Equation Editor or MathType inside word processors in the Windows environment,
% you end up with the same problems and have to fiddle \myemph{every}
% sub- and superscript individually. A browse through the accompanying
% sample document, \pkg{mtsample.tex}, will show that this can amount to
% hundreds of little equations. I challenge anyone to rewrite that
% document with one of the popular wordprocessors and still be sane
% afterwards :-)}:
%
% \begin{itemize}
%
% \item
% For an \cmd{\overline}, $\overline{f}^a_b$, the superscript moves up
% to the height of the overline, which is fine for vector notation,
% but the subscript kerning is lost, because the symbol is set
% inside a box with italic correction added (App. G of the
% \TeX{}book). If the subscript is added inside the \cmd{\overline}
% construct, $\overline{f_b}^a$, the overline is stretched, which is
% acceptable only when the subscript is part of the symbol itself.
% The subscript kerning can be corrected by attaching the subscript
% to the symbol and the superscript to the overline and then overtyping
% (\cmd{\rlap} or \cmd{\llap}) them while using a phantom symbol (without
% subscript) for the overline,
% \begin{sample}
% |\leavevmode\rlap{$f^{}_b$}$\overline{\phantom{f}}^a$|
% \end{sample}
% which gives \leavevmode\rlap{$f^{}_b$}$\overline{\phantom{f}}^a$.
%
% The \cmd{\leavevmode} command is nessesary to prevent the symbol
% being spread over two lines when it is the first token in a new
% paragraph (\TeX{} in vertical mode).
%
% Care must be taken with the sequence in which the two parts
% overlap when the symbol (including subscript) is wider than the
% overline,
% \leavevmode\rlap{$f^{}_{abcd}$}$\overline{\phantom{f}}^a$,
% because the subscript will then run into the following text.
%
% \item
% If a math accent is added to the overline, \usebox{\AccentBox},
% the superscript goes to the level of the accent (except if the
% \pkg{accents}\ package is loaded). This can be remedied by
% controlling the height of the accented overline construction with
% \cmd{\smash} and \cmd{\vphantom} commands,
% ^^A
% \begin{sample}
% |\leavevmode\rlap{$f^{}_b$}%|\\
% |${\smash{\dot{\overline{\phantom{f}}}}\vphantom{\overline{f}}}^a$|
% \end{sample}
% %
% which gives
% \leavevmode\rlap{${\smash{\dot{\overline{\phantom{f}}}}^^A
%                    \vphantom{\overline{f}}}^a$}^^A
%                 {$f^{}_b$}.
%
% \item
% For an |\overrightarrow| in vector notation,
% ($\overrightarrow{i}_a$, ~$\overrightarrow{iiii}_a\,$), the
% construction of the stretchable arrow results in an arrow wider
% than most symbols, with the symbol centred below it.
% The subscript ended up far removed from the symbol.
% For multiple symbols, the arrow width is equal to the box containing
% the letters, resulting in better-looking subscripts
% (but still without the subscript kerning).
% The previous procedure can be used to correct the
% subscript kerning, except that additional white space must be
% inserted before the symbol to centre it beneath the arrow.
%
% \begin{sample}
% |\newlength{\ArrWdth}\settowidth{\ArrWdth}{$\overrightarrow{i}$}|\\
% |\newlength{\SymWdth}\settowidth{\SymWdth}{$i$}|\\
% |\newlength{\Wspace}\setlength{\Wspace}{0.5\ArrWdth}|\\
% |\addtolength{\Wspace}{-0.5\SymWdth}|\\
% |\leavevmode\rlap{$\hspace*{\Wspace}i^{}_b$}%|\\
% |${\smash{\dot{\overrightarrow{\phantom{i}}}}%|\\
% |              \vphantom{\overrightarrow{i}}}^a$|
% \end{sample}
% \newlength{\ArrWdth}\settowidth{\ArrWdth}{$\overrightarrow{i}$}^^A
% \newlength{\SymWdth}\settowidth{\SymWdth}{$i$}^^A
% \newlength{\Wspace}\setlength{\Wspace}{0.5\ArrWdth}^^A
% \addtolength{\Wspace}{-0.5\SymWdth}^^A
% which gives \leavevmode\rlap{\hspace*{\Wspace}$i^{}_b$}${^^A
% \smash{\dot{\overrightarrow{\phantom{i}}}}\vphantom{\overrightarrow{i}}}^a$^^A
%
% The commands can be optimized by using saveboxes, \myemph{but}
% the symbols will not scale correctly when used as sub- or
% superscripts or in the \cmd{\tfrac} macro.  A solution is to nest
% the commands inside a \cmd{\mathpalette} environment, but be warned,
% this is very expensive!
% The commands \cmd{\phantom}, \cmd{\smash}, \cmd{\overrightarrow}
% (in \pkg{amsmath}) are already inside \cmd{\mathpalette} macros, and
% \TeX{} calls the arguments of a \cmd{\mathpalette} macro four times
% before deciding on the dimensions.
% The next piece of code simulates a \cmd{\mathpalette} by using the
% \pkg{amsmath} command \cmd{\text}. Take a guess at the value of |cnt|.
% \begin{sample}
% |\newcounter{cnt}|\\
% |\newcommand*{\Sym}[1]{%|\\
% |    \boldsymbol{{#1\addtocounter{cnt}{1}}}}|\\
% |$Q_\text{\leavevmode\rlap%|\\
% |      {$\Sym{x}_i$}%|\\
% |     ${\smash{\dot{\overrightarrow{\phantom{\Sym{x}}}}}%|\\
% |       \vphantom{\overrightarrow{\Sym{x}^j}}}$%|\\
% |   }$ ~~cnt $=$ \thecnt|
% \end{sample}

% It gives the correct scaled tensor \usebox{\nested} (proper white
% space before symbol not implemented)
%
% This piece of code is nominated as the worst \LaTeX{} code, in
% terms of efficiency, that has ever been written. But before voting,
% load the \pkg{accents} package, rerun it, and then cast
% your vote.
%
% \item
% The shape of the arrow tip of the |\overrightarrow| command was
% probably not designed for this type of application and is much too
% broad in the final CM font version. This broad arrow shape is
% incidentally one of last changes by Prof.~Knuth to the CM font symbols.
%
% The PostScript version of the CM fonts typesets the arrow much
% better, but it is highly likely that it is still the old outdated
% version of the symbol. So, people at Y\&Y or Bluesky, \myemph{please}
% do not update your font.
%
% \item
% The subscript heights differ for the cases with and without
% superscripts, $x_b,\; x_b^a$. This is not very satisfactory for a
% consistent matrix-tensor notation, but it can be remedied by
% inserting a dummy superscript, |$x^{}_b$|, which then gives
% $x^{}_b$, $x_b^a$.
%
% \end{itemize}
%
% The \MT\ package was developed to overcome (some of) the above-mentioned
% problems and to typeset the \Hass{} matrix tensor symbols in a
% consistent manner.
%
%
% \subsection{To do's}
%
% \begin{itemize}
% \item
% The vertical spacing between the symbols and the lines and arrows
% differs, \aSb{E}, \bSa{E}. This problem cannot be fixed easily
% and would need some additional struts or even a rewriting of the
% arrows and lines commands.
%
% \item
% For the purists: The ends of the |\overrightarrow| are rounded
% (ligature of symbols), while the ends of the |\overline| are squared
% (\TeX{} line drawing).
%
% \item
% \MT\ does not yet work with the \pkg{xspace} package.
% \end{itemize}
%
% \subsection{Bugs, etc.}
%
% I am sure there is much room for improvement, because
% I am a \TeX{}natic and not a \TeX{}pert and to quote
% Knuth from the \TeX{}book:
% \begin{quote}
% {\slshape\small Always remember, however, that there's usually
% a simpler and better way to do something than the first way that
% pops into your head. You may not have to resort to any subterfuge
% at all, since \TeX{} is able to do lots of things in a
% straightforward way. Try for simple solutions first.}
% \end{quote}
%
% Please send all bug reports, suggestions, advice or code improvements
% to:
% \medskip
%
% \fbox{\begin{minipage}{\textwidth}
% \centering
% Danie Els\\
%
% \smallskip
% Department of Mechanical Engineering\\
% University of Stellenbosch\\
% Private Bag X1, Matieland 7602, South Africa.\\
% e-mail: \texttt{dnjels@sun.ac.za}
% \end{minipage}}
%
% \StopEventually{
%
%    \begin{thebibliography}{7}
%
%    \bibitem{Hass93a}
%    \Hass, W.~C.,
%    ``Matrix Tensor Notation Part I. Rectilinear Orthogonal Coordinates,''
%    \textsl{Comput. Math. Appl.},
%    \textbf{26}(3), 1993, pp. 55--93.
%
%    \bibitem{Hass93b}
%    \Hass, W.~C.,
%    ``Matrix Tensor Notation Part II. Skew and Curved Coordinates,''
%    \textsl{Comput. Math. Appl.},
%    \textbf{29}(11), 1993, pp. 1--103.
%
%    \end{thebibliography}
%
% } ^^A end StopEventually
%
% \clearpage
% \section{The Code: \pkg{mattens.sty}}
%    \setlength{\parskip}{\smallskipamount}
%
%    \begin{macrocode}
%<*package>
%    \end{macrocode}
%
%    \subsection{Identification}
%
%    \begin{macrocode}
\NeedsTeXFormat{LaTeX2e}
\ProvidesPackage{mattens}[2001/12/09 v1.0 DNJ Els]
%    \end{macrocode}
%
%    \subsection{Packages}
%
%    The \pkg{amsmath} package is loaded to provide the scalable
%    \cmd{\overrightarrow} and \cmd{\underrightarrow} commands, as
%    well as the \cmd{\boldsymbol} command for setting bold math
%    symbols.
%
%    \begin{macrocode}
\RequirePackage{amsmath}
%    \end{macrocode}
%
%    \subsection{Workaround commands}
%
%    \begin{macro}{\MT@Overarrow}
%    \begin{macro}{\MT@Underarrow}
%    We define over- and under-arrows that bypass the
%    \cmd{\mathpalette} part of the \pkg{amsmath} macros
%    \cmd{\overrightarrow} and \cmd{\underrightarrow}. It uses
%    the \pkg{amsmath} internal macros \cmd{\overarrow@},
%    \cmd{\underarrow@} and \cmd{\rightarrowfill@}.
%    The first parameter |#1| consists of math styles \cmd{\displaystyle},
%    \cmd{\textstyle}, etc.  The second parameter |#2| is the symbol
%    or character.
%    \begin{macrocode}
\newcommand{\MT@Overarrow}[2]{\overarrow@{\rightarrowfill@}{#1}{#2}}
\newcommand{\MT@Underarrow}[2]{\underarrow@{\rightarrowfill@}{#1}{#2}}
%    \end{macrocode}
%    \end{macro}
%    \end{macro}
%
%    \begin{macro}{\MT@Overline}
%    \begin{macro}{\MT@Underline}
%    Make over- and underlines with the same calling syntax as
%    the arrows.
%    \begin{macrocode}
\newcommand{\MT@Overline}[2]{{#1\overline{#2}}}
\newcommand{\MT@Underline}[2]{{#1\underline{#2}}}
%    \end{macrocode}
%    \end{macro}
%    \end{macro}
%
%    \begin{macro}{\xusebox}
%    The \cmd{\usebox} command does not function properly when the
%    \pkg{pdftex.def} driver is loaded, because \pkg{pdftex} does not implement
%    a colour stack such as in the \pkg{dvips} driver, but simulate
%    it at \TeX{} macro level.  The \cmd{\xusebox} is a workaround
%    where an additional \cmd{\begingroup}, \cmd{\endgroup} is placed around
%    the \cmd{\usebox} command\footnote{Thanks to Heiko Oberdiek for this
%    workaround}. A strut is added after the box to regain its height.
%    \begin{macrocode}
\newcommand{\xusebox}[1]{%
  \setbox\z@\null%
  \ht\z@\ht#1%
  \dp\z@\dp#1%
  \begingroup%
     \usebox{#1}%
  \endgroup%
  \box\z@}
%    \end{macrocode}
%    \end{macro}
%
%
%    \subsection{Options}
%
%    \begin{macro}{\MT@SymbStrt}
%    \begin{macro}{\SetSymbStrut}
%    Struts to set all the lines and arrows at
%    predetermined heights and depths.
%    \begin{macrocode}
\newcommand*{\MT@SymbStrt}{}
\newcommand*{\SetSymbStrut}[1]{\renewcommand*{\MT@SymbStrt}{#1}}
\SetSymbStrut{\relax}
\DeclareOption{mathstrut}{\SetSymbStrut{\mathstrut}}
%    \end{macrocode}
%    \end{macro}
%    \end{macro}
%
%    \begin{macro}{\MT@SymbFnt}
%    \begin{macro}{\SetSymbFont}
%    Initialize the symbol font formatting commands.
%    \begin{macrocode}
\newcommand*{\MT@SymbFnt}{\relax}
\newcommand*{\SetSymbFont}[1]{\renewcommand*{\MT@SymbFnt}{#1}}
\SetSymbFont{\boldsymbol}
\DeclareOption{noformat}{\SetSymbFont{\relax}}
%    \end{macrocode}
%    \end{macro}
%    \end{macro}
%
%    Process the options
%    \begin{macrocode}
\DeclareOption*{%
    \PackageWarning{mattens}{Unknown option ‘\CurrentOption’}}
\ProcessOptions\relax
%    \end{macrocode}
%
%
%    \subsection{Initialize}
%
%    Define skip lengths for insertion in front of sub- and
%    superscripts.
%    \begin{macrocode}
\newmuskip{\MT@Askip}
\newmuskip{\MT@Bskip}
\newmuskip{\MT@SPskip}
\newmuskip{\MT@SBskip}
%    \end{macrocode}
%
%    \begin{macro}{\SetArrowSkip}
%    \begin{macro}{\SetBarSkip}
%    \begin{macro}{\SetSymSuPSkip}
%    \begin{macro}{\SetSymSuBSkip}
%    Define commands to set or change the skip lengths and set initial values.
%    \begin{macrocode}
\newcommand*{\SetArrowSkip}[1]{\MT@Askip#1}
\newcommand*{\SetBarSkip}[1]{\MT@Bskip#1}
\newcommand*{\SetSymSuPSkip}[1]{\MT@SPskip#1}
\newcommand*{\SetSymSuBSkip}[1]{\MT@SBskip#1}
\SetArrowSkip{0mu}
\SetBarSkip{1mu}
\SetSymSuBSkip{0mu}
\SetSymSuPSkip{0mu}
%    \end{macrocode}
%    \end{macro}
%    \end{macro}
%    \end{macro}
%    \end{macro}
%
%
%    \subsection{Main \MT\ commands}
%
%    Setup command templates and lengths to function as global
%    variables and pointers.
%
%    \begin{macro}{\MT@accent}
%    The \cmd{\MT@accent} command points
%    to the math accent that are inserted as the optional argument
%    inside the main \MT\ commands.
%
%    \begin{macrocode}
\newcommand*{\MT@accent}{}
%    \end{macrocode}
%    \end{macro}
%
%    \begin{macro}{\MT@cmd}
%    \begin{macro}{\MT@@cmd}
%    The commands \cmd{\MT@cmd} and \cmd{\MT@cmd} do the actual
%    typesetting of the symbols.
%    \begin{macrocode}
\newcommand*{\MT@cmd}{}
\newcommand*{\MT@@cmd}{}
%    \end{macrocode}
%    \end{macro}
%    \end{macro}
%
%     They can be seen
%    as function pointer that are set with |\let| commands inside
%    the main \MT\ commands to point to specific commands.
%
% \newcommand{\RA}{\ensuremath{\,\mapsto\,}}
%
%    \begin{tabbing}
%    \hskip2pc\=\hskip3pc\=\hskip12pc\=\kill
%    \>\textsl{Cmd} \> \textsl{Primary command} \> \textsl{Secondary command}\\[.75ex]
%    \>|\aS|:   \>|\MT@cmd| \RA |\MT@OverAandB|,   \>|\MT@@cmd| \RA |\MT@Overarrow|\\
%    \>|\bS|:   \>|\MT@cmd| \RA |\MT@OverAandB|,   \>|\MT@@cmd| \RA |\MT@Overline|\\
%    \>|\Sa|:   \>|\MT@cmd| \RA |\MT@UnderAandB|,  \>|\MT@@cmd| \RA |\MT@Underarrow|\\
%    \>|\Sb|:   \>|\MT@cmd| \RA |\MT@UnderAandB|,  \>|\MT@@cmd| \RA |\MT@Underline|\\
%    \>|\bSb|:  \>|\MT@cmd| \RA |\MT@DoubleAandB|, \>|\MT@@cmd| \RA |\MT@@bSb| \\
%    \>|\aSb|:  \>|\MT@cmd| \RA |\MT@DoubleAandB|, \>|\MT@@cmd| \RA |\MT@@aSb|\\
%    \>|\bSa|:  \>|\MT@cmd| \RA |\MT@DoubleAandB|, \>|\MT@@cmd| \RA |\MT@@bSa| \\
%    \>|\aSa|:  \>|\MT@cmd| \RA |\MT@DoubleAandB|, \>|\MT@@cmd| \RA |\MT@@aSa|\\
%    \>|\bCSb|: \>|\MT@cmd| \RA |\MT@DoubleAandB|, \>|\MT@@cmd| \RA |\MT@@bCSb|\\
%    \>|\aCSa|: \>|\MT@cmd| \RA |\MT@DoubleAandB|, \>|\MT@@cmd| \RA |\MT@@aCSa|\\
%    \end{tabbing}
%
%    \begin{macro}{\MT@SuBskip}
%    \begin{macro}{\MT@SuPskip}
%    Define math skip lengths to insert in front of the sub- and
%    superscripts. The values are set inside the main \MT\ commands
%    according to the type of symbol.
%    \begin{macrocode}
\newmuskip\MT@SuBskip
\newmuskip\MT@SuPskip
%    \end{macrocode}
%    \end{macro}
%    \end{macro}
%
%    The following commands are the main \MT\ commands that set up
%    all the global variables and pointers and then calls the command
%    \cmd{\MT@GetScrpts} to extract the sub- and superscripts and
%    which then in turn calls the global pointer \cmd{\MT@cmd} to
%    do the typesetting. It first checks if the command is starred and
%    set the bold italic formatting accordingly.
%
%    \begin{macro}{\ifMT@bold}
%    A boolean if bold italic formatting is on or off
%    \begin{macrocode}
\newif\ifMT@bold
\MT@boldfalse
%    \end{macrocode}
%    \end{macro}
%
%    \begin{macro}{\aS}
%    \begin{macro}{\@aS}
%    Type the tensor: \aS{x}
%    \begin{macrocode}
\DeclareRobustCommand*{\aS}{%
   \@ifstar{\MT@boldfalse\@aS}{\MT@boldtrue\@aS}}
%    \end{macrocode}
%    \begin{macrocode}
\newcommand*{\@aS}[2][\@empty]{%
   \let\MT@accent=#1%
   \let\MT@cmd=\MT@OverAandB%
   \let\MT@@cmd=\MT@Overarrow%
   \MT@SuPskip=\MT@Askip%
   \MT@SuBskip=\MT@SBskip%
   \MT@GetScrpts{#2}}%
%    \end{macrocode}
%    \end{macro}
%    \end{macro}
%
%    \begin{macro}{\bS}
%    \begin{macro}{\@bS}
%    Type the tensor: \bS{x}
%    \begin{macrocode}
\DeclareRobustCommand*{\bS}{%
   \@ifstar{\MT@boldfalse\@bS}{\MT@boldtrue\@bS}}
%    \end{macrocode}
%    \begin{macrocode}
\newcommand*{\@bS}[2][\@empty]{%
   \let\MT@accent=#1%
   \let\MT@cmd=\MT@OverAandB%
   \let\MT@@cmd=\MT@Overline%
   \MT@SuPskip=\MT@Bskip%
   \MT@SuBskip=\MT@SBskip%
   \MT@GetScrpts{#2}}%
%    \end{macrocode}
%    \end{macro}
%    \end{macro}
%
%    \begin{macro}{\Sa}
%    \begin{macro}{\@Sa}
%    Type the tensor: \Sa{x}
%    \begin{macrocode}
\DeclareRobustCommand*{\Sa}{%
   \@ifstar{\MT@boldfalse\@Sa}{\MT@boldtrue\@Sa}}
%    \end{macrocode}
%    \begin{macrocode}
\newcommand*{\@Sa}[2][\@empty]{%
   \let\MT@accent=#1%
   \let\MT@cmd=\MT@UnderAandB%
   \let\MT@@cmd=\MT@Underarrow%
   \MT@SuPskip=\MT@SPskip%
   \MT@SuBskip=\MT@Askip%
   \MT@GetScrpts{#2}}%
%    \end{macrocode}
%    \end{macro}
%    \end{macro}
%
%    \begin{macro}{\Sb}
%    \begin{macro}{\@Sb}
%    Type the tensor: \Sb{x}
%    \begin{macrocode}
\DeclareRobustCommand*{\Sb}{%
   \@ifstar{\MT@boldfalse\@Sb}{\MT@boldtrue\@Sb}}
%    \end{macrocode}
%    \begin{macrocode}
\newcommand*{\@Sb}[2][\@empty]{%
   \let\MT@accent=#1%
   \let\MT@cmd=\MT@UnderAandB%
   \let\MT@@cmd=\MT@Underline%
   \MT@SuPskip=\MT@SPskip%
   \MT@SuBskip=\MT@Bskip%
   \MT@GetScrpts{#2}}%
%    \end{macrocode}
%    \end{macro}
%    \end{macro}
%
%    \begin{macro}{\bSb}
%    \begin{macro}{\@bSb}
%    Type the tensor: \bSb{E}
%    \begin{macrocode}
\DeclareRobustCommand*{\bSb}{%
   \@ifstar{\MT@boldfalse\@bSb}{\MT@boldtrue\@bSb}}
%    \end{macrocode}
%    \begin{macrocode}
\newcommand*{\@bSb}[2][\@empty]{%
   \let\MT@accent=#1%
   \let\MT@cmd=\MT@DoubleAandB%
   \let\MT@@cmd=\MT@@bSb%
   \MT@SuPskip=\MT@Bskip%
   \MT@SuBskip=\MT@Bskip%
   \MT@GetScrpts{#2}}
%    \end{macrocode}
%    \end{macro}
%    \end{macro}
%
%    \begin{macro}{\aSb}
%    \begin{macro}{\@aSb}
%    Type the tensor: \aSb{E}
%    \begin{macrocode}
\DeclareRobustCommand*{\aSb}{%
   \@ifstar{\MT@boldfalse\@aSb}{\MT@boldtrue\@aSb}}
%    \end{macrocode}
%    \begin{macrocode}
\newcommand*{\@aSb}[2][\@empty]{%
   \let\MT@accent=#1%
   \let\MT@cmd=\MT@DoubleAandB%
   \let\MT@@cmd=\MT@@aSb%
   \MT@SuPskip=\MT@Askip%
   \MT@SuBskip=\MT@Bskip%
   \MT@GetScrpts{#2}}
%    \end{macrocode}
%    \end{macro}
%    \end{macro}
%
%    \begin{macro}{\bSa}
%    \begin{macro}{\@bSa}
%    Type the tensor: \bSa{E}
%    \begin{macrocode}
\DeclareRobustCommand*{\bSa}{%
   \@ifstar{\MT@boldfalse\@bSa}{\MT@boldtrue\@bSa}}
%    \end{macrocode}
%    \begin{macrocode}
\newcommand*{\@bSa}[2][\@empty]{%
   \let\MT@accent=#1%
   \let\MT@cmd=\MT@DoubleAandB%
   \let\MT@@cmd=\MT@@bSa%
   \MT@SuPskip=\MT@Bskip%
   \MT@SuBskip=\MT@Askip%
   \MT@GetScrpts{#2}}
%    \end{macrocode}
%    \end{macro}
%    \end{macro}
%
%    \begin{macro}{\aSa}
%    \begin{macro}{\@aSa}
%    Type the tensor: \aSa{E}
%    \begin{macrocode}
\DeclareRobustCommand*{\aSa}{%
   \@ifstar{\MT@boldfalse\@aSa}{\MT@boldtrue\@aSa}}
%    \end{macrocode}
%    \begin{macrocode}
\newcommand*{\@aSa}[2][\@empty]{%
   \let\MT@accent=#1%
   \let\MT@cmd=\MT@DoubleAandB%
   \let\MT@@cmd=\MT@@aSa%
   \MT@SuPskip=\MT@Askip%
   \MT@SuBskip=\MT@Askip%
   \MT@GetScrpts{#2}}
%    \end{macrocode}
%    \end{macro}
%    \end{macro}
%
%    \begin{macro}{\bCSb}
%    \begin{macro}{\@bCSb}
%    Type the tensor: \bCSb{\omega}
%    \begin{macrocode}
\DeclareRobustCommand*{\bCSb}{%
   \@ifstar{\MT@boldfalse\@bCSb}{\MT@boldtrue\@bCSb}}
%    \end{macrocode}
%    \begin{macrocode}
\newcommand*{\@bCSb}[2][\@empty]{%
   \let\MT@accent=#1%
   \let\MT@cmd=\MT@DoubleAandB%
   \let\MT@@cmd=\MT@@bCSb%
   \MT@SuPskip=\MT@Bskip%
   \MT@SuBskip=\MT@Bskip%
   \MT@GetScrpts{#2}}
%    \end{macrocode}
%    \end{macro}
%    \end{macro}
%
%    \begin{macro}{\aCSa}
%    \begin{macro}{\@aCSa}
%    Type the tensor: \aCSa{\omega}
%    \begin{macrocode}
\DeclareRobustCommand*{\aCSa}{%
   \@ifstar{\MT@boldfalse\@aCSa}{\MT@boldtrue\@aCSa}}
%    \end{macrocode}
%    \begin{macrocode}
\newcommand*{\@aCSa}[2][\@empty]{%
   \let\MT@accent=#1%
   \let\MT@cmd=\MT@DoubleAandB%
   \let\MT@@cmd=\MT@@aCSa%
   \MT@SuPskip=\MT@Askip%
   \MT@SuBskip=\MT@Askip%
   \MT@GetScrpts{#2}}
%    \end{macrocode}
%    \end{macro}
%    \end{macro}
%
%
%    \subsection{Sub- and superscripts}
%
%    This part of the code looks ahead for sub- and superscripts and
%    put those tokens into the global variables (commands)
%    \cmd{\MT@suB} and \cmd{\MT@suP}.  If there are sub-and
%    superscripts present then the flags \cmd{\ifMT@@suB} and
%    \cmd{\ifMT@@suP} are set accordingly.  These variables are stored
%    for the final typesetting with the commands \cmd{\MT@setsuB},
%    \cmd{\MT@setsuBS} and \cmd{\MT@setsuP}.
%
%    \begin{macro}{\ifMT@@suB}
%    \begin{macro}{\ifMT@@suP}
%    Define flags that are set inside the extraction commands if sub-
%    or superscripts are present.
%
%    \begin{macrocode}
\newif\ifMT@@suB
\newif\ifMT@@suP
%    \end{macrocode}
%    \end{macro}
%    \end{macro}
%
%    \begin{macro}{\MT@suB}
%    \begin{macro}{\MT@suP}
%    Define global variables (commands) that contains the extracted
%    sub- and superscripts. These commands are redefined inside the
%    extraction commands.
%
%    \begin{macrocode}
\newcommand*{\MT@suB}{}
\newcommand*{\MT@suP}{}
%    \end{macrocode}
%    \end{macro}
%    \end{macro}
%
%    \begin{macro}{\MT@GetScrpts}
%    The first extraction command. It looks ahead for |^| or |_|,
%    if not present, then calls the typesetting command pointer
%    \cmd{\MT@cmd} with empty sub- and superscripts, otherwise passes
%    the tokens on to the next extraction commands.
%
%    \begin{macrocode}
\newcommand*{\MT@GetScrpts}[1]{%
    \@ifnextchar^%
        {\MT@GetsuP{#1}}%
        {\@ifnextchar_%
            {\MT@GetsuB{#1}}%
            {\MT@@suBfalse%
             \MT@@suPfalse%
             \ensuremath{\MT@cmd{#1}}}}}
%    \end{macrocode}
%    \end{macro}
%
%    \begin{macro}{\MT@GetsuP}
%    Extract and typeset calls of the form \meta{Sym}|^|\meta{sup}
%    if there are no further |_| tokens available, otherwise pass the
%    tokens on to the next extraction command.
%
%    \begin{macrocode}
\def\MT@GetsuP#1^#2{%
    \@ifnextchar_%
        {\MT@GetsuPsuB{#1}{#2}}%
        {\MT@@suBfalse%
         \MT@@suPtrue%
         \renewcommand*{\MT@suP}{#2}%
         \ensuremath{\MT@cmd{#1}}}}
%    \end{macrocode}
%    \end{macro}
%
%    \begin{macro}{\MT@GetsuB}
%    Extract and typeset calls of the form \meta{Sym}|_|\meta{sub}
%    if there are no further |^| tokens available, otherwise pass the
%    tokens on to the next extraction command.
%
%    \begin{macrocode}
\def\MT@GetsuB#1_#2{%
    \@ifnextchar^%
        {\MT@GetsuBsuP{#1}{#2}}%
        {\MT@@suBtrue%
         \MT@@suPfalse%
         \renewcommand*{\MT@suB}{#2}%
         \ensuremath{\MT@cmd{#1}}}}
%    \end{macrocode}
%    \end{macro}
%
%    \begin{macro}{\MT@GetsuPsuB}
%    Extract and typeset calls of the form
%    \meta{Sym}|^|\meta{sup}|_|\meta{sub}.
%
%    \begin{macrocode}
\def\MT@GetsuPsuB#1#2_#3{%
    \MT@@suBtrue%
    \MT@@suPtrue%
    \renewcommand*{\MT@suB}{#3}%
    \renewcommand*{\MT@suP}{#2}%
    \ensuremath{\MT@cmd{#1}}}
%    \end{macrocode}
%    \end{macro}
%
%    \begin{macro}{\MT@GetsuBsuP}
%    Extract and typeset calls of the form
%    \meta{Sym}|_|\meta{sub}|^|\meta{sup}.
%
%    \begin{macrocode}
\def\MT@GetsuBsuP#1#2^#3{%
    \MT@@suBtrue%
    \MT@@suPtrue%
    \renewcommand*{\MT@suB}{#2}%
    \renewcommand*{\MT@suP}{#3}%
    \ensuremath{\MT@cmd{#1}}}
%    \end{macrocode}
%    \end{macro}
%
%    The next commands are for the actual typesetting of the
%    saved sub- and superscripts. These commands are called from
%    within the main typesetting command pointed to by \cmd{\MT@cmd}.
%
%    \begin{macro}{\MT@setsuB}
%    Type |_{|\meta{mskip}\meta{sub}|}| if subscript is present.
%
%    \begin{macrocode}
\newcommand*{\MT@setsuB}{%
    \ifMT@@suB
        _{\mskip\MT@SuBskip\relax\MT@suB}%
    \fi}
%    \end{macrocode}
%    \end{macro}
%
%    \begin{macro}{\MT@setsuBS}
%    Type |^{}_{|\meta{mskip}\meta{sub}|}| if subscript is present.
%
%    \begin{macrocode}
\newcommand*{\MT@setsuBS}{%
    \ifMT@@suB
        ^{}_{\mskip\MT@SuBskip\relax\MT@suB}%
    \fi}
%    \end{macrocode}
%    \end{macro}
%
%    \begin{macro}{\MT@setsuP}
%    Type |^{|\meta{mskip}\meta{sup}|}| if superscript is present.
%
%    \begin{macrocode}
\newcommand*{\MT@setsuP}{%
   \ifMT@@suP
       ^{\mskip\MT@SuPskip\relax\MT@suP}%
   \fi}
%    \end{macrocode}
%    \end{macro}
%
%
%    \subsection{Symbol formatting}
%
%    \begin{macro}{\MT@Symb}
%    This command type |{|\meta{strut}\meta{font-cmd}\meta{symb}|}|,
%    the formatted symbol preceded by the selected strut. It is called
%    from within the main typesetting commands.
%
%    \begin{macrocode}
\newcommand*{\MT@Symb}[1]{%
   \MT@SymbStrt%
   \ifMT@bold\MT@SymbFnt#1\else#1\fi}
%    \end{macrocode}
%    \end{macro}
%
%    \begin{macro}{\MT@SymbC}
%    Puts a widetilde over the symbol for the cross product tensors.
%    \begin{macrocode}
\newcommand*{\MT@SymbC}[1]{%
   \MT@SymbStrt\widetilde{%
   \ifMT@bold\MT@SymbFnt#1\else#1\fi}}
%    \end{macrocode}
%    \end{macro}
%
%
%    \subsection{Main typesetting commands}
%
%    The commands in this section are the ones pointed to by
%    the \cmd{\MT@cmd} and \cmd{\MT@@cmd} commands to perform
%    the typesetting of the full tensor symbol.
%
%    Declare some save boxes
%    \begin{macrocode}
\newsavebox{\MT@Abox}   % for overline/arrow
\newsavebox{\MT@Sbox}   % for symbol
\newsavebox{\MT@Tbox}   % for tempories
\newsavebox{\MT@APbox}  % for overline/arrow phantom
\newsavebox{\MT@SPbox}  % for symbol phantom
%    \end{macrocode}
%    and some lengths.
%    \begin{macrocode}
\newlength{\MT@SPwdth}  % symbol width
\newlength{\MT@BPwdth}  % Bar width
\newlength{\MT@Wwdth}   % leading whitespace width
%    \end{macrocode}
%
%    \begin{macro}{\MT@OverAandB}
%    This command generates the tensor symbols \aS{e}{} and \bS{e}.
%    It utilizes the \cmd{\mathpalette} macro for the sizing of the
%    final tensor. \LaTeX{} commands \cmd{\smash} and \cmd{\phantom}
%    with embedded \cmd{\mathpalette} calls are avoided to prevent
%    nested \cmd{\mathchoice} calls.
%    \begin{macrocode}
\newcommand*{\MT@OverAandB}{%
   \mathpalette\MT@@OverAandB}
%    \end{macrocode}
%    \end{macro}
%
%    \begin{macro}{\MT@@OverAandB}
%    For this command the first parameter |#1| is supplied by
%    \cmd{\mathpalette} and consists of math styles \cmd{\displaystyle},
%    \cmd{\textstyle}, etc.  The second parameter |#2| is the original
%    \meta{symbol} from the call \cmd{\MT@cmd}|{|\meta{symbol}|}|.
%
%    The command \cmd{\xusebox} is used in place \cmd{\usebox} because
%    of compatibility problems with \pkg{pdftex.def}.
%
%    \begin{macrocode}
\newcommand*{\MT@@OverAandB}[2]{%
%    \end{macrocode}
%
%    \begin{Indent}{5em}
%    Set the symbol inside a box for measurement purposes.
%    \end{Indent}
%
%    \begin{macrocode}
      \sbox{\MT@Tbox}{$\m@th#1\MT@Symb{#2}$}%
%    \end{macrocode}
%
%    \begin{Indent}{5em}
%    Make phantom symbol box (empty) with size identical to symbol.
%    \end{Indent}
%
%    \begin{macrocode}
      \setbox\MT@SPbox\null%
      \ht\MT@SPbox\ht\MT@Tbox%
      \dp\MT@SPbox\dp\MT@Tbox%
      \wd\MT@SPbox\wd\MT@Tbox%
%    \end{macrocode}
%
%    \begin{Indent}{5em}
%    Make overline/overarrow over phantom symbol box for measurement.
%    \end{Indent}
%
%    \begin{macrocode}
      \sbox{\MT@APbox}{$\m@th#1\MT@@cmd{#1}{\copy\MT@SPbox}$}%
%    \end{macrocode}
%
%    \begin{Indent}{5em}
%    Calculate width difference between symbol and arrow/overline.
%    \end{Indent}
%
%    \begin{macrocode}
      \setlength{\MT@Wwdth}{\the\wd\MT@APbox}%
      \addtolength{\MT@Wwdth}{-\the\wd\MT@SPbox}%
%    \end{macrocode}
%
%    \begin{Indent}{5em}
%    Make final symbol box with white space in front to center is
%    beneath the arrow/over line and subscript that follows.
%    \end{Indent}
%
%    \begin{macrocode}
      \sbox{\MT@Sbox}{$\m@th#1\hskip 0.5\MT@Wwdth\MT@Symb{#2}\MT@setsuBS$}%
%    \end{macrocode}
%
%    \begin{Indent}{5em}
%    Add math accent to overline/overarrow and reset box dimensions to
%    original.
%    \end{Indent}
%
%    \begin{macrocode}
      \sbox{\MT@Tbox}{$\m@th#1\MT@accent{\xusebox{\MT@APbox}}$}%
      \ht\MT@Tbox\ht\MT@APbox%
      \dp\MT@Tbox\dp\MT@APbox%
%    \end{macrocode}
%
%    \begin{Indent}{5em}
%    Final overline/overarrow box including accent and superscript at end.
%    \end{Indent}
%
%    \begin{macrocode}
      \sbox{\MT@Abox}{$\m@th#1\xusebox{\MT@Tbox}\MT@setsuP$}%
%    \end{macrocode}
%
%    \begin{Indent}{5em}
%    Overtype the symbol and the overline/overarrow boxes. The wider
%    box of the two is typed last to ensure that the spacing after
%    the full tensor symbol is correct.
%    \end{Indent}
%
%    \begin{macrocode}
      \ifdim\wd\MT@Abox<\wd\MT@Sbox%
          \leavevmode\rlap{\xusebox\MT@Abox}{\xusebox\MT@Sbox}%
      \else%
           \leavevmode\rlap{\xusebox\MT@Sbox}{\xusebox\MT@Abox}%
      \fi}
%    \end{macrocode}
%    \end{macro}
%
%    \begin{macro}{\MT@UnderAandB}
%    \begin{macro}{\MT@@UnderAandB}
%    This command generates the tensor symbols \Sa{e}{} and \Sb{e}.
%    It is identical to the previous command except the sub- and
%    superscripts are swapped.
%    \begin{macrocode}
\newcommand*{\MT@UnderAandB}{%
   \mathpalette\MT@@UnderAandB}
%    \end{macrocode}
%    \begin{macrocode}
\newcommand*{\MT@@UnderAandB}[2]{%
      \sbox{\MT@Tbox}{$\m@th#1\MT@Symb{#2}$}%
      \setbox\MT@SPbox\null%
      \ht\MT@SPbox\ht\MT@Tbox%
      \dp\MT@SPbox\dp\MT@Tbox%
      \wd\MT@SPbox\wd\MT@Tbox%
      \sbox{\MT@APbox}{$\m@th#1\MT@@cmd{#1}{\copy\MT@SPbox}$}%
      \setlength{\MT@Wwdth}{\the\wd\MT@APbox}%
      \addtolength{\MT@Wwdth}{-\the\wd\MT@SPbox}%
      \sbox{\MT@Sbox}{$\m@th#1\hskip 0.5\MT@Wwdth\MT@Symb{#2}\MT@setsuP$}%
      \sbox{\MT@Tbox}{$\m@th#1\MT@accent{\xusebox{\MT@APbox}}$}%
      \ht\MT@Tbox\ht\MT@APbox%
      \dp\MT@Tbox\dp\MT@APbox%
      \sbox{\MT@Abox}{$\m@th#1\xusebox{\MT@Tbox}\MT@setsuB$}%
      \ifdim\wd\MT@Abox<\wd\MT@Sbox%
         \leavevmode\rlap{\xusebox\MT@Abox}{\xusebox\MT@Sbox}%
      \else%
         \leavevmode\rlap{\xusebox\MT@Sbox}{\xusebox\MT@Abox}%
      \fi}
%    \end{macrocode}
%    \end{macro}
%    \end{macro}
%
%    \begin{macro}{\MT@@bSb}
%    \begin{macro}{\MT@@bSa}
%    \begin{macro}{\MT@@aSb}
%    \begin{macro}{\MT@@aSa}
%    \begin{macro}{\MT@@bCSb}
%    \begin{macro}{\MT@@aCSa}
%    These commands are pointed to by \cmd{\MT@@cmd} and called from
%    within \cmd{\MT@DoubleAandB}. It has the same calling syntax as
%    the \cmd{\MT@Overarrow} and \cmd{\MT@Underarrow} commands.
%    \begin{macrocode}
\newcommand*{\MT@@bSb}[2]{\MT@Overline{#1}{\MT@Underline{#1}{\MT@Symb{#2}}}}
\newcommand*{\MT@@aSb}[2]{\MT@Overarrow{#1}{\MT@Underline{#1}{\MT@Symb{#2}}}}
\newcommand*{\MT@@bSa}[2]{\MT@Overline{#1}{\MT@Underarrow{#1}{\MT@Symb{#2}}}}
\newcommand*{\MT@@aSa}[2]{\MT@Overarrow{#1}{\MT@Underarrow{#1}{\MT@Symb{#2}}}}
\newcommand*{\MT@@bCSb}[2]{\MT@Overline{#1}{\MT@Underline{#1}{\MT@SymbC{#2}}}}
\newcommand*{\MT@@aCSa}[2]{\MT@Overarrow{#1}{\MT@Underarrow{#1}{\MT@SymbC{#2}}}}
%    \end{macrocode}
%    \end{macro}
%    \end{macro}
%    \end{macro}
%    \end{macro}
%    \end{macro}
%    \end{macro}
%
%    \begin{macro}{\MT@DoubleAandB}
%    \begin{macro}{\MT@@DoubleAandB}
%    This command is used for the remaining tensor symbols and is not
%    so complex compared to the previous commands.
%
%    \begin{macrocode}
\newcommand*{\MT@DoubleAandB}{%
  \mathpalette\MT@@DoubleAandB}
%    \end{macrocode}
%    \begin{macrocode}
\newcommand*{\MT@@DoubleAandB}[2]{%
      \sbox{\MT@Abox}{$\m@th#1\MT@@cmd{#1}{#2}$}%
      \sbox{\MT@Tbox}{$\m@th#1\MT@accent{\xusebox{\MT@Abox}}$}%
      \ht\MT@Tbox\ht\MT@Abox%
      \dp\MT@Tbox\dp\MT@Abox%
      \xusebox{\MT@Tbox}\MT@setsuP\MT@setsuB}
%    \end{macrocode}
%    \end{macro}
%    \end{macro}
%
%^^A         {\smash{\MT@accent{\MT@@cmd{#1}{#2}}}\vphantom{\MT@@cmd{#1}{#2}}}%
%^^A         \MT@setsuP%
%^^A         \MT@setsuB}
%
%    \subsection{A save/recall box utility}
%
%    \begin{macro}{\DeclareSBox}
%    \begin{macro}{\MT@cname}
%    \begin{macro}{\MT@bname}
%    \begin{macro}{\MT@bnameuse}
%
%    For the command
%    \cmd{\DeclareSBox}\marg{$\backslash$cmd}\marg{contents},
%    it saves the \meta{contents} in a savebox
%    |\MTbox@|\textit{cmd}. It then defines a command |\|\textit{cmd}
%    that expands to |\usebox{\MTbox@|\textit{cmd}|}|.
%
%    First a safety check if internal commands exist.
%    \begin{macrocode}
\newcommand*{\MT@cname}{}    % ->  <cmd>
\newcommand*{\MT@bname}{}    % ->  MTbox@<cmd>
\newcommand*{\MT@bnameuse}{} % ->  \MTbox@<cmd>
%    \end{macrocode}
%
%    Here the main command
%
%    \begin{macrocode}
\newcommand{\DeclareSBox}[2]{%
     \edef\MT@cname{\expandafter\@gobble\string#1}%
     \edef\MT@bname{MTbox@\MT@cname}%
     \@ifundefined{\MT@cname}{%
          \edef\MT@bnameuse{\csname\MT@bname\endcsname}%
          \expandafter\newbox\MT@bnameuse%
          \global\sbox{\MT@bnameuse}{#2}%
%    \end{macrocode}
%
%    \begin{Indent}{8em}
%    In the next declaration |\xdef| was replaced
%    by |\protected@xdef| and an additional |\protect| was added before
%    the |\xusebox| command. This was nessesary to be compatable with
%    \pkg{pdftex.def}\footnote{Thanks to Heiko Oberdiek and Robin Fairbairns
%    for this advice.}.
%    \end{Indent}
%
%    \begin{macrocode}
          \protected@xdef#1{\protect\xusebox{\MT@bnameuse}}%
          }%
          {\PackageError{mattens}%
               {Command \space\protect#1\space allready\space defined!}%
               {Use\space a\space different\space name}}}
%    \end{macrocode}
%    \end{macro}
%    \end{macro}
%    \end{macro}
%    \end{macro}
%
%
%
% \subsection{Helper utility functions}
%
%
%    \begin{macro}{\cdot}
%    \begin{macro}{\trnsp}
%    \begin{macro}{\norm}
%    \begin{macro}{\SB}
%    The following is a set of very simple utility macro's inside \MT\
%    to ease the typesetting of matrix--tensor stuff. They can all be
%    used in text mode.
%
%    \begin{macrocode}
\newcommand*{\tdot}{\ensuremath{{\cdot}}}                % Center dot
\newcommand*{\trnsp}{\ensuremath{\mathsf{T}}}            % Matrix transpose
\providecommand*{\norm}[1]{\ensuremath{\lVert{#1}\rVert}}% Norm delimiters
\newcommand*{\SB}[1]{\ensuremath{\left[\, #1\right]}}    % Square brackets
%    \end{macrocode}
%    \end{macro}
%    \end{macro}
%    \end{macro}
%    \end{macro}
%
%
%    \begin{macrocode}
%</package>
%    \end{macrocode}
% \clearpage
% \Finale
% \setcounter{IndexColumns}{2}\PrintIndex
% \PrintChanges
%
\endinput