mathtools (2feb22)

git-svn-id: svn://tug.org/texlive/trunk@61856 c570f23f-e606-0410-a88d-b1316a301751

6 files changed, 359 insertions, 137 deletions

diff --git a/Master/texmf-dist/source/latex/mathtools/empheq.dtx b/Master/texmf-dist/source/latex/mathtools/empheq.dtx
index 7f4b76b8ae5..c0ecdec0270 100644
--- a/Master/texmf-dist/source/latex/mathtools/empheq.dtx
+++ b/Master/texmf-dist/source/latex/mathtools/empheq.dtx
@@ -438,8 +438,8 @@ and the derived files
 %  \subsection{Using the \env{empheq} environment}
 %
 %  The package defines a single environment
-%  \SpecialEnvIndex{empheq}\env{empheq} and the usage is kind of straight
-%  forward:
+%  \SpecialEnvIndex{empheq}\env{empheq} and the usage is kind of
+%  straightforward:
 %  \begin{codesyntax}
 %    |\begin{empheq}|\oarg{markup instructions}\marg{\AmS{} env_name}\\
 %    \mbox{}\quad\meta{contents of \AmS{} environment}\\
@@ -462,7 +462,7 @@ and the derived files
 %      E&=mc^2 + \int_a^a x\, dx
 %    \end{empheq}
 %  Maybe not the most impressive example, but as you can see the
-%  contents of the environment is exactly the same as for the regular
+%  contents of the environment are exactly the same as for the regular
 %  \env{align*} evironment from \pkg{amsmath}. The rest of the \AmS{}
 %  environments are chosen the same way by typing the name as the
 %  mandatory argument of \env{empheq} with the exception of the
@@ -572,7 +572,7 @@ and the derived files
 %  \end{codesyntax}
 %  The key \key{box} specifies the kind of box you would like to put
 %  around the display. It can be any kind of box, as long as the
-%  contents of the box is situated on the baseline like in a
+%  contents of the box are situated on the baseline like in a
 %  \fbox{\cs{fbox}}.
 %  \begin{verbatim}
 %  \begin{empheq}[box=\fbox]{align}
@@ -614,7 +614,7 @@ and the derived files
 %  this manual features centered math displays.} you may want the
 %  math display and not the outer box to align at the left margin (or
 %  rather: the indentation). If you make sure the contents of the
-%  outer box is centered horizontally inside the box, \key{marginbox}
+%  outer box are centered horizontally inside the box, \key{marginbox}
 %  will align it properly. You shouldn't set both \key{box} and
 %  \key{marginbox} at the same time, as this is surely not what you
 %  want and the package will silently use the last one in the list.
@@ -762,7 +762,7 @@ and the derived files
 %  versions prior to and including~0.7e. If you have documents produced
 %  with versions prior to~0.7e, then you have to load the package
 %  \pkg{empheq07} instead. \pkg{empheq07} now exists as a separate package
-%  package with its own documentation, but I strongly recommend switching
+%  with its own documentation, but I strongly recommend switching
 %  to the new version because it is so much better.
 %
 %  \subsection{Package options}
@@ -802,7 +802,7 @@ and the derived files
 %  \opt{ntheorem} option. In order for this to work properly, an
 %  \pkg{amsmath} bug\footnote{See the \LaTeX{} Bugs Database
 %  \url{http://www.latex-project.org/cgi-bin/ltxbugs2html} under
-%  \AmS\LaTeX{} problem report 3624.} is fixed. For more information
+%  \AmS-\LaTeX{} problem report 3624.} is fixed. For more information
 %  on this option see \S \vref{sec:ntheorem-support}.
 %
 %  \subsubsection{Using \env{multline}}
@@ -930,14 +930,14 @@ and the derived files
 %  for the pseudo environment |\[ ... \]| (it's not really an
 %  environment), \footnote{With the option \opt{oldmultline} the
 %  \env{multline} and \env{multline*} environments aren't supported
-%  either because their syntax in \pkg{empheq} then differ from their
+%  either because their syntax in \pkg{empheq} then differs from their
 %  syntax in \pkg{amsmath}.} because a)~you don't really need markup
 %  instructions for a one line display, and b)~would you really like
 %  a syntax like
 %  \begin{verbatim}
 %    \[[box=\fbox] a=b \]
 %  \end{verbatim}
-%  where its difficult to see whether or not there is a typo?
+%  where it's difficult to see whether or not there is a typo?
 %  Choosing \opt{overload} is meant for people who don't want to
 %  change their entire document into \pkg{empheq} syntax. I have no
 %  problems with that; just be careful when you fiddle with
@@ -1089,7 +1089,7 @@ and the derived files
 %  packages where \pkg{empheq} has to provide workarounds and they
 %  can be divided into two categories.
 %  \begin{description}
-%    \item[Compatibility] Some packages affect \LaTeX' labelling
+%    \item[Compatibility] Some packages affect \LaTeX's labelling
 %    mechanism and since \pkg{empheq} internally has to turn off
 %    labels and related code temporarily, hooks must be provided for
 %    these packages. Examples of such packages are \pkg{hyperref} and
@@ -1184,7 +1184,7 @@ and the derived files
 %  be lost. In the future \pkg{ntheorem} should be able to test for
 %  this and add \verb|\usetagform{default}| automatically.
 %
-%  Users who use \verb|\usetagform| to get another tag design, should
+%  Users who use \verb|\usetagform| to get another tag design should
 %  make sure to postpone this configuration until \emph{after} loading
 %  \pkg{ntheorem}. 
 %
@@ -1270,7 +1270,7 @@ and the derived files
 %
 %  The good news is that this is where \pkg{empheq} sets in.
 %  Basically all you need to do is to use the \env{empheq}
-%  environment to type set your equations inside the theorem
+%  environment to typeset your equations inside the theorem
 %  environments:
 %  \begin{verbatim}
 %    \begin{Theorem}
@@ -1346,7 +1346,7 @@ and the derived files
 %  sub-formula inside the \cs{left}-\cs{right} pair is to be
 %  vertically centered and given its height $h_1$ and its depth $h_2$
 %  we want to produce a delimiter with total height $h$, where  $h =
-%  2 \max(h_1,h_2)$. \TeX' rules on this is that the minimum
+%  2 \max(h_1,h_2)$. \TeX's rules on this are that the minimum
 %  delimiter size $h_{\min}$ must meet the requirements
 %  \[
 %    h_{\min}\geq h \frac{f}{1000} \quad\land \quad h_{\min}\geq h-\delta
@@ -1437,7 +1437,7 @@ and the derived files
 %
 %  \subsection{About \texorpdfstring{$\cs{eqref}$}{\textbackslash eqref}}
 %
-%  Internally \env{empheq} separate the displayed math from
+%  Internally \env{empheq} separates the displayed math from
 %  the corresponding equation numbers such that we can add special
 %  delimiters or boxes. This is done by nullifying (or rather
 %  conveniently redefining) an internal command called
@@ -1709,7 +1709,7 @@ and the derived files
 %  \bibitem{fancybox}
 %    Timothy Van Zandt,
 %    \emph{The \pkg{fancybox} package} Version 1.3,
-%    2000/09/19
+%    2000/09/19.
 %    (Available from CTAN as file \texttt{fancybox.sty}.)
 %
 % \bibitem{Raht03}
@@ -1728,19 +1728,19 @@ and the derived files
 %  \changes{v1.06}{2004/03/13}{Added \pkg{calc} to the \refname}
 %  \bibitem{Thorup:calc:1998}
 %  Kresten~Krab Thorup, Frank Jensen, and Chris Rowley.
-%  \emph{The {\pkg{calc}} package}, Version 4.1b, 1998/07/07,
+%  \emph{The {\pkg{calc}} package}, Version 4.1b, 1998/07/07.
 %  (Available from CTAN as file \texttt{calc.dtx}.)
 %
 %  \bibitem{ntheorem}
 %    Wolfgang May and Andreas Schlechte,
 %    \emph{The \pkg{ntheorem} package} Version 1.203,
-%    2002/01/07,
+%    2002/01/07.
 %    (Available from CTAN as file \texttt{ntheorem.dtx}.)
 %
 %  \changes{v2.10}{2004/07/26}{Added \pkg{showkeys} to the \refname}
 %  \bibitem{Carlisle:showkeys:1997}
 %  David Carlisle. \emph{The {\pkg{showkeys}} package}, v3.12,
-%  1997/06/12, (Available from CTAN as file \texttt{showkeys.dtx}.)
+%  1997/06/12. (Available from CTAN as file \texttt{showkeys.dtx}.)
 %
 %  \end{thebibliography}
 %
diff --git a/Master/texmf-dist/source/latex/mathtools/empheq.ins b/Master/texmf-dist/source/latex/mathtools/empheq.ins
index 632545df724..265efeb2bbc 100644
--- a/Master/texmf-dist/source/latex/mathtools/empheq.ins
+++ b/Master/texmf-dist/source/latex/mathtools/empheq.ins
@@ -33,7 +33,7 @@
 \input docstrip.tex
 \Msg{************************************************************************}
 \Msg{* Installation}
-\Msg{* Package: empheq 2017/03/31 v2.15 empheq}
+\Msg{* Package: empheq 2020/03/24 v2.16 empheq}
 \Msg{************************************************************************}
 
 \keepsilent
diff --git a/Master/texmf-dist/source/latex/mathtools/mathtools.dtx b/Master/texmf-dist/source/latex/mathtools/mathtools.dtx
index b065615eb04..15cf76b3233 100644
--- a/Master/texmf-dist/source/latex/mathtools/mathtools.dtx
+++ b/Master/texmf-dist/source/latex/mathtools/mathtools.dtx
@@ -2,7 +2,7 @@
 %
 % Copyright (C) 2004-2011 by Morten Hoegholm
 % Copyright (C) 2012-2019 by Lars Madsen
-% Copyright (C) 2020      by Lars Madsen, The LaTeX3 team
+% Copyright (C) 2020-     by Lars Madsen, The LaTeX3 team
 %
 % This work may be distributed and/or modified under the
 % conditions of the LaTeX Project Public License, either
@@ -133,7 +133,7 @@ and the derived files
 %<*driver>
 \NeedsTeXFormat{LaTeX2e}
 \ProvidesFile{mathtools.drv}%
-  [2021/04/12 v1.27 mathematical typesetting tools]
+  [2022/02/02 v1.28 mathematical typesetting tools]
 \documentclass{ltxdoc}
   
 \IfFileExists{fourier.sty}{\usepackage{fourier}}{}
@@ -239,6 +239,7 @@ and the derived files
 }
 
 
+
 \expandafter\def\expandafter\MakePrivateLetters\expandafter{%
   \MakePrivateLetters  \catcode`\_=11\relax
 }
@@ -294,6 +295,16 @@ and the derived files
 \def\theindex{\MTtheindex\MakePrivateLetters}
 
 
+\NewDocumentCommand\Framebox{ o O{c} m }{%
+  \IfNoValueTF{#1}{%
+    \framebox{\footnotesize\strut #3}%
+  }{%
+    \framebox[#1][#2]{\footnotesize\strut #3}%
+  }%
+}
+
+
+
 %\usepackage[draft]{fixme}
 %\fxsetup{
 % multiuser,
@@ -322,7 +333,7 @@ colorlinks,
 %
 %  \GetFileInfo{mathtools.drv}
 %
-%  \CheckSum{3529}
+%  \CheckSum{3581}
 %
 %  \title{The \pkg{mathtools} package\thanks{This file has version number
 %  \fileversion, last revised \filedate.}}
@@ -335,7 +346,7 @@ colorlinks,
 %  \begin{abstract}
 %    \noindent The \pkg{mathtools} package is an extension package to
 %    \pkg{amsmath}. There are two things on \pkg{mathtools}' agenda:
-%    (1)~correct various bugs/defeciencies in \pkg{amsmath} until
+%    (1)~correct various bugs/deficiencies in \pkg{amsmath} until
 %    these are fixed by the \AmS{} and (2)~provide useful tools
 %    for mathematical typesetting, be it a small macro for
 %    typesetting a prescript or an underbracket, or entirely new
@@ -400,7 +411,7 @@ colorlinks,
 %  The option \opt{fixamsmath} (default) fixes two bugs in
 %  \pkg{amsmath}.\footnote{See the online \LaTeX{} bugs database
 %  \url{http://www.latex-project.org/cgi-bin/ltxbugs2html} under
-%  \AmS\LaTeX{} problem reports 3591 and 3614.} Should you for some
+%  \AmS-\LaTeX{} problem reports 3591 and 3614.} Should you for some
 %  reason not want to fix these bugs then just add the option
 %  \opt{donotfixamsmathbugs} (if you can do it without typos). The
 %  reason for this extremely long name is that I really don't see why
@@ -553,14 +564,14 @@ colorlinks,
 %  \endgroup
 %  Notice how the limit of the right summation sign is typeset in a
 %  more compact style than the left. It is because \TeX{} sets the
-%  limits of operators in a \emph{cramped} style. For each of \TeX'
+%  limits of operators in a \emph{cramped} style. For each of \TeX's
 %  four math styles (\cs{displaystyle}, \cs{textstyle},
 %  \cs{scriptstyle}, and \cs{scriptscriptstyle}), there also exists a
 %  cramped style that doesn't raise exponents as much. Besides in the
 %  limits of operators, \TeX{} also automatically uses these cramped
 %  styles in radicals such as \cs{sqrt} and in the denominators of
 %  fractions, but unfortunately there are no primitive commands that
-%  allows you to detect crampedness or switch to it.
+%  allow you to detect crampedness or switch to it.
 %
 %  \pkg{mathtools} offers the command \cs{cramped} which forces a
 %  cramped style in normal un-cramped math. Additionally you can
@@ -594,7 +605,7 @@ colorlinks,
 %  \end{quote}
 %  Typesetting on a grid is generally considered quite desirable, but
 %  as the second line of the example shows, the exponents of $2$
-%  causes the line to be too tall for the normal value of
+%  cause the line to be too tall for the normal value of
 %  \cs{baselineskip}, so \TeX{} inserts a \cs{lineskip} (normal value
 %  is \the\lineskip). In order to circumvent the problem, we can
 %  force a cramped style so that the exponents aren't raised as much:
@@ -785,7 +796,7 @@ colorlinks,
 %  \label{sec:swapping}
 %
 %  One feature that the plain old \env{equation} environment has that
-%  the \AmS\ environments does not (because of technical reasons), is
+%  the \AmS\ environments do not (because of technical reasons) is
 %  the feature of using less space above the equation if the situation
 %  presents itself. The \AmS\ environments cannot do this, but one can
 %  manually, using  
@@ -822,7 +833,7 @@ colorlinks,
 %
 %  In this section various tools for altering the appearance of tags
 %  are shown. All of the tools here can be used at any point in the
-%  document but they should probably be affect the whole document, so
+%  document but they should probably affect the whole document, so
 %  the preamble is the best place to issue them.
 %
 %  \subsubsection{The appearance of tags}
@@ -896,6 +907,13 @@ colorlinks,
 %    \SpecialKeyIndex{showmanualtags}$\key{showmanualtags}=\texttt{true}\vert\texttt{false}$\\
 %    \SpecialUsageIndex{\refeq}\cs{refeq}\marg{label}
 %  \end{codesyntax}
+%  First of, one should always use \cs{eqref} when referring to
+%  equation numbers. When \opt{showonlyrefs} is true, we monitor
+%  \cs{eqref}\marg{label}, and those used will get an equation number,
+%  whereas those not used will not. Note: We do \emph{not} monitor the
+%  normal \cs{ref} command! See the follow paragraph for situations
+%  for what to do when \cs{eqref} cannot be used to refer to the equation. 
+% 
 %  An equation where the tag is produced with a manual \cs{tag*}
 %  shouldn't be referenced with the normal \cs{eqref} because that
 %  would format it according to the current tag format. Using just
@@ -994,8 +1012,8 @@ colorlinks,
 %  \cs{ref}. 
 %
 %  \medskip\noindent\textbf{BUG 1:} Unfortunately the use of the
-%  \key{showonlyref} introduce a bug within amsmath's typesetting
-%  of formula versus equation number. This bug manifest itself by
+%  \key{showonlyref} introduces a bug within amsmath's typesetting
+%  of formula versus equation number. This bug manifests itself by
 %  allowing formulas to be typeset close to or over the equation
 %  number.  Currently no general fix is known, other than making sure
 %  that one's formulas are not long enough to touch the equation
@@ -1007,7 +1025,7 @@ colorlinks,
 %  number is recorded such that the formula or the equation number can
 %  be moved (if necessary) in the typesetting part. When
 %  \key{showonlyref} is enabled, the width of the equation number
-%  depend on whether or not this number is referred~to. To determine
+%  depends on whether or not this number is referred~to. To determine
 %  this, we need to know the current label. But the current label is
 %  \emph{not} known in the measuring phase. Thus the measured width is
 %  always zero (because no label equals not referred to) and therefore
@@ -1019,7 +1037,7 @@ colorlinks,
 % \pkg{ntheorem} option \key{thmmarks} is active. The shown equation
 % numbers may come out wrong (seems to be multiplied by 2). Or the end
 % marker may be placed in the wrong place if a proof ends with a
-% displayed formula, and that formula is not refered to.
+% displayed formula, and that formula is not referred to.
 %
 % There are two possible solutions to this both involving \pkg{empheq}.  
 % The easiest fix is to add the following line
@@ -1029,7 +1047,7 @@ colorlinks,
 % before loading \pkg{ntheorem}. But the \texttt{overload} option of
 % course disables things like \cs{intertext} and \cs{shotintertext}.
 %
-% The other thing to try is to use drop the \texttt{overload} option
+% The other thing to try is to drop the \texttt{overload} option
 % and use \env{empheq} on the very last expression, as in
 % \begin{verbatim}
 %   \begin{empheq}{align}
@@ -1125,10 +1143,22 @@ colorlinks,
 %  \cs{xLeftrightarrow} we added a space to the argument(s), making
 %  the arrow slightly longer and moving the argument away from the
 %  large arrow head.
-% 
-% 
-%
 %
+%  \begin{codesyntax}
+%    \SpecialUsageIndex{\xlongrightarrow}
+%    \cs{xlongrightarrow}\oarg{sub}\marg{sup}\texttt{~~~~}
+%    \SpecialUsageIndex{\xlongleftarrow}
+%    \cs{xlongleftarrow}\oarg{sub}\marg{sup}\texttt{~~~~}
+% \end{codesyntax}
+%  \FeatureRequest{rbrito {\footnotesize (issue \#12)}}{added 2022}%
+% Similar to \cs{xright/leftarrow} but based on the \emph{long}
+% versions. For short arguments it stays the same length as the
+% \cs{long...} base arrow.
+% \begin{align*}
+%   A & \longrightarrow B & A & \longleftarrow B \\
+%   A & \xlongrightarrow[b]{a} B & A & \xlongleftarrow[b]{a} B \\
+%   A & \xlongrightarrow[below]{above} B & A & \xlongleftarrow[below]{above} B \\
+% \end{align*}
 %
 %  \subsubsection{Braces and brackets}
 %
@@ -1205,13 +1235,13 @@ colorlinks,
 %  As \cs{overbrace} has the exact same problems, there are good
 %  reasons for \pkg{mathtools} to make redefinitions of
 %  \cs{underbrace} and \cs{overbrace}. These new versions work
-%  equally well in all font sizes and fixes the spacing issues and
+%  equally well in all font sizes and fix the spacing issues and
 %  apart from working with the default Computer Modern fonts, they
 %  also work with the packages \pkg{mathpazo}, \pkg{pamath},
 %  \pkg{fourier}, \pkg{eulervm}, \pkg{cmbright}, and \pkg{mathptmx}.
 %  If you use the \pkg{ccfonts} to get the full Concrete fonts, the
 %  original version saved under the names \cs{LaTeXunderbrace} and
-%  \cs{LaTeXoverbrace} are better, due to of the special design of
+%  \cs{LaTeXoverbrace} is better, due to the special design of
 %  the Concrete extensible braces. In that case you should probably
 %  just add the lines
 %  \begin{verbatim}
@@ -1270,7 +1300,7 @@ colorlinks,
 %  type valid in the usual \env{array} environment.
 %
 %  While we are at it, we also provide fenced versions of the
-%  \env{smallmatrix} environment, To keep up with the naming of the
+%  \env{smallmatrix} environment. To keep up with the naming of the
 %  large matrix environments, we provide both a starred and a
 %  non-starred version. Since \env{smallmatrix} is defined in a
 %  different manner than the \env{matrix} environment, the option to
@@ -1322,9 +1352,9 @@ colorlinks,
 % the default is \cs{,}.
 %
 % As an extra trick the fences will behave as open and closing fences
-% in constract to their auto-scaling nature.\footnote{\cs{left} and
+% despite their auto-scaling nature.\footnote{\cs{left} and
 % \cs{right} creates an \emph{inner} construction, and not as one
-% might expect something where a preceeding \cs{sin} sees an opening
+% might expect something where a preceding \cs{sin} sees an opening
 % fence, thus the space before or after may be too large. Inside this
 % construction they behave.}
 % 
@@ -1358,19 +1388,21 @@ colorlinks,
 %  right and preceded by a hard space of size \key{lastline-preskip}.
 %  Both these hard spaces have a default value of \cs{multlinegap}.
 %  Here we use a `t' in the first optional argument denoting a
-%  top-aligned building block (the default is `c').
+%  top-aligned building block (the default is `c').\footnote{The helper macro
+%  \cs{Framebox}\marg{...} is equivalent to
+%  \cs{framebox}\marg{\cs{footnotesize}\cs{strut} ...}}
 %  \begin{verbatim}
 %    \[
 %      A = \begin{multlined}[t]
-%            \framebox[4cm]{first} \\
-%            \framebox[4cm]{last}
+%            \Framebox[4cm]{first} \\
+%            \Framebox[4cm]{last}
 %          \end{multlined} B
 %    \]
 %  \end{verbatim}
 %    \[
 %      A = \begin{multlined}[t]
-%            \framebox[4cm]{first} \\
-%            \framebox[4cm]{last}
+%            \Framebox[4cm]{first} \\
+%            \Framebox[4cm]{last}
 %          \end{multlined} B
 %    \]
 %  Note also that \env{multlined} gives you access to an extended
@@ -1379,25 +1411,25 @@ colorlinks,
 %  \begin{verbatim}
 %    \[
 %      \begin{multlined}
-%        \framebox[.65\columnwidth]{First line}        \\
-%        \framebox[.5\columnwidth]{Second line}        \\
+%        \Framebox[.65\columnwidth]{First line}        \\
+%        \Framebox[.5\columnwidth]{Second line}        \\
 %        \shoveleft{L+E+F+T}                           \\
 %        \shoveright{R+I+G+H+T}                        \\
 %        \shoveleft[1cm]{L+E+F+T}                      \\
 %        \shoveright[\widthof{$R+I+G+H+T$}]{R+I+G+H+T} \\
-%        \framebox[.65\columnwidth]{Last line}
+%        \Framebox[.65\columnwidth]{Last line}
 %      \end{multlined}
 %    \]
 %  \end{verbatim}
 %  \[
 %    \begin{multlined}
-%      \framebox[.65\columnwidth]{First line} \\
-%      \framebox[.5\columnwidth]{Second line} \\
+%      \Framebox[.65\columnwidth]{First line} \\
+%      \Framebox[.5\columnwidth]{Second line} \\
 %      \shoveleft{L+E+F+T}         \\
 %      \shoveright{R+I+G+H+T}         \\
 %      \shoveleft[1cm]{L+E+F+T}         \\
 %      \shoveright[\widthof{$R+I+G+H+T$}]{R+I+G+H+T}         \\
-%      \framebox[.65\columnwidth]{Last line}
+%      \Framebox[.65\columnwidth]{Last line}
 %    \end{multlined}
 %  \]
 %
@@ -1406,15 +1438,15 @@ colorlinks,
 %  \begin{verbatim}
 %    \[
 %      \begin{multlined}[b][7cm]
-%        \framebox[4cm]{first} \\
-%        \framebox[4cm]{last}
+%        \Framebox[4cm]{first} \\
+%        \Framebox[4cm]{last}
 %      \end{multlined} = B
 %    \]
 %  \end{verbatim}
 %    \[
 %       \begin{multlined}[b][7cm]
-%            \framebox[4cm]{first} \\
-%            \framebox[4cm]{last}
+%            \Framebox[4cm]{first} \\
+%            \Framebox[4cm]{last}
 %          \end{multlined} = B
 %    \]
 %  There can be two optional arguments (position and width) and
@@ -1428,14 +1460,14 @@ colorlinks,
 %  not work as expected. The implementation contains an `invisible'
 %  line after the first \env{multline} row, inside an \env{array} this
 %  line is no longer `invisible' because \env{array} sets
-%  \cs{baselineskip} to zero. Currently we have no general workaround
+%  \cs{baselineskip} to zero. We have no general workaround
 %  for this. 
 %
 %  \medskip\noindent
 %  \textbf{Bug 2:}
 %  \CommentAdded{2015/11/12}  
 %  Due to the way \env{multlined} is implemented, certain
-%  constructions does not work inside \env{multlined}. We have added a
+%  constructions do not work inside \env{multlined}. We have added a
 %  hook (\cs{MultlinedHook}) that can be added to. The default value
 %  is a fix for \env{subarray} and \env{crampedsubarray} and thus for
 %  \cs{substack} and \cs{crampedsubstack} (and a few others, thus add
@@ -1484,7 +1516,7 @@ colorlinks,
 %    \cs{end}\arg{cases*}
 %  \end{codesyntax}
 %  \FeatureRequest{Lars Madsen}{2004/07/01}
-%  Anyone who have tried to use an integral in the regular
+%  Anyone who has tried to use an integral in the regular
 %  \env{cases} environment from \pkg{amsmath} will have noticed that
 %  it is set as
 %  \[
@@ -1552,16 +1584,19 @@ colorlinks,
 %    \SpecialEnvIndex{\MoveEqLeft}\cs{MoveEqLeft}\oarg{number}
 %  \end{codesyntax}
 %  \ProvidedBy{Lars Madsen}{2008/06/05} In \cite{Swanson}, Ellen
-%  Swanson recommends that when ever one has a long displayed formula,
+%  Swanson recommends that whenever one has a long displayed formula,
 %  spanning several lines, and it is unfeasible to align against a
 %  relation within the first line, then all lines in the display
 %  should be aligned at the left most edge of the first line, and all
 %  subsequent lines should be indented by 2\,em (or if needed by a
 %  smaller amount). That is we are talking about displays that end up
-%  looking like this
+%  looking like this\footnote{Maintainer (daleif)'s note: This is one
+%  of my most used constructions whenever I edit manuscripts. I'd
+%  rather use this than for example \env{multline} as I find it gives
+%  the text a more consistent look.}
 %  \begin{align*}
-%    \MoveEqLeft \framebox[10cm][c]{Long first line}\\
-%    & = \framebox[6cm][c]{ \hphantom{g} 2nd line}\\ 
+%    \MoveEqLeft \Framebox[10cm][c]{Long first line}\\
+%    & = \Framebox[6cm][c]{2nd line}\\ 
 %    & \leq \dots
 %  \end{align*}
 %  Traditionally one could do this by starting subsequent lines by
@@ -1569,8 +1604,8 @@ colorlinks,
 %  was made using \cs{MoveEqLeft}:
 %  \begin{verbatim}
 %  \begin{align*}
-%    \MoveEqLeft \framebox[10cm][c]{Long first line}\\
-%    & = \framebox[6cm][c]{ \hphantom{g} 2nd line}\\ 
+%    \MoveEqLeft \Framebox[10cm][c]{Long first line}\\
+%    & = \Framebox[6cm][c]{2nd line}\\ 
 %    & \leq \dots
 %  \end{align*}
 %  \end{verbatim}
@@ -1581,22 +1616,22 @@ colorlinks,
 %  to accommodate the extra distance to the alignment point:
 %  \begin{verbatim}
 %  \begin{align*}
-%    \MoveEqLeft[3] \framebox[10cm][c]{Part 1}\\
-%     = {} & \framebox[8cm][c]{2nd line}\\ 
-%          & + \framebox[4cm][c]{ last part}
+%    \MoveEqLeft[3] \Framebox[10cm][c]{Part 1}\\
+%     = {} & \Framebox[8cm][c]{2nd line}\\ 
+%          & + \Framebox[4cm][c]{last part}
 %  \end{align*}
 %  \end{verbatim}
 %  \begin{align*}
-%    \MoveEqLeft[3] \framebox[10cm][c]{Long first line}\\
-%     = {} & \framebox[6cm][c]{  2nd line}\\ 
-%          & + \framebox[4cm][c]{ last part}
+%    \MoveEqLeft[3] \Framebox[10cm][c]{Long first line}\\
+%     = {} & \Framebox[6cm][c]{2nd line}\\ 
+%          & + \Framebox[4cm][c]{last part}
 %  \end{align*}
 %
 %
 % \noindent\textbf{Caveat regarding \cs{MoveEqLeft}}: If the first
 % part of the equation starts with say \verb|[a]|, \cs{MoveEqLeft} may
 % attempt to eat it! You can prevent this by specifying the optional
-% argument (remember the default is the same as \cs{MoveEqLeft[2]} or
+% argument (remember the default is the same as \cs{MoveEqLeft[2]}) or
 % by using \cs{MoveEqLeft\{\}}.
 %
 %  \subsubsection{Boxing a single line in an alignment}
@@ -1634,8 +1669,8 @@ colorlinks,
 %                 & = g(x)
 % \end{align*}
 % One can have multiple boxes on each line, and the
-% >>\texttt{\textnormal{\&}}\quad right hand side<< can even be
-% missing. Here is an example of how the padding in the box can be changed
+% ``\texttt{\textnormal{\&}}\quad right hand side'' can even be
+% missing. Here is an example of how the padding in the box can be changed.
 % \begin{verbatim}
 % \begin{align*}
 %   \setlength\fboxsep{1em}
@@ -1648,7 +1683,7 @@ colorlinks,
 %   \Aboxed{ f(x) &= 0 } & \Aboxed{ g(x) &= b} \\
 %   \Aboxed{ h(x) }      & \Aboxed{ i(x) }   
 % \end{align*}
-% Note how the \cs{fboxsep} change only affect the box coming
+% Note how the \cs{fboxsep} change only affects the box coming
 % immediately after it.  
 %
 %  \marginpar{\strut\\%
@@ -1661,6 +1696,33 @@ colorlinks,
 % use of \texttt{\&}. Just add a set of braces around the construction
 % you want to hide. 
 %
+% \medskip\noindent\textbf{Tip:} At times users want a \cs{Aboxed}
+% with a different type of box. To help we provide a \cs{Aboxed} builder:
+%  \begin{codesyntax}
+%    \SpecialUsageIndex{\MakeAboxedCommand}\cs{MakeAboxedCommand}\cs{Aboxedname}\cs{boxmacro}
+%  \end{codesyntax}
+% where \cs{boxname} should be a macro taking a single argument. The
+% normal \cs{Aboxed} is the same as
+% \verb|\MakeAboxedCommand\Aboxed\fbox|. Thus you can do
+% \newcommand\myboxA[1]{\fcolorbox{gray}{yellow}{#1}}
+% \newcommand\myboxB[1]{{\fboxsep=5pt\fboxrule=2pt\fbox{#1}}}
+% \MakeAboxedCommand\AboxedA\myboxA
+% \MakeAboxedCommand\AboxedB\myboxB
+% \begin{align*}
+%   \AboxedA{ f(x) &= x^2 } & \AboxedB{ f(x) &= x^2 }
+% \end{align*}
+% via
+% \begin{verbatim}
+% \newcommand\myboxA[1]{\fcolorbox{gray}{yellow}{#1}}
+% \newcommand\myboxB[1]{{\fboxsep=5pt\fboxrule=2pt\fbox{#1}}}
+% \MakeAboxedCommand\AboxedA\myboxA
+% \MakeAboxedCommand\AboxedB\myboxB
+% \begin{align*}
+%   \AboxedA{ f(x) &= x^2 } & \AboxedB{ f(x) &= x^2 } 
+% \end{align*}
+% \end{verbatim}
+% 
+%
 %  \subsubsection{Adding arrows between lines in an alignment}
 %
 %  This first macro is a bit misleading, it is only intended to be
@@ -1713,7 +1775,7 @@ colorlinks,
 %
 % \subsubsection{Centered \texorpdfstring{\cs{vdots}}{\textbackslash vdots}}
 %
-%  If one want to mark a vertical continuation, there is
+%  If one wants to mark a vertical continuation, there is
 %  the \verb?\vdots? command, but combine this with an alignment and
 %  we get something rather suboptimal
 % \FeatureRequest{Bruno Le Floch \\(and many others)}{2011/01/25}
@@ -1735,7 +1797,7 @@ colorlinks,
 %    \SpecialKeyIndex{shortvdotsadjustabove}\makebox{$\key{shortvdotsadjustabove}=\meta{length}$}\\
 %    \SpecialKeyIndex{shortvdotsadjustbelow}\makebox{$\key{shortvdotsadjustbelow}=\meta{length}$}
 %  \end{codesyntax}
-%  Two examples in one
+% Two examples in one
 % \begin{verbatim}
 % \begin{align*}
 %   a &= b              \\
@@ -1754,7 +1816,7 @@ colorlinks,
 %     & = d
 % \end{align*}
 % Thus \verb?\vdotswithin{=}? creates a box corresponding to
-% \verb?{}={}? and typeset a >>$\vdots$<< centered inside it. When
+% \verb?{}={}? and typesets a ``$\vdots$'' centered inside it. When
 % doing this as a normal line in an alignment leaves us with excessive
 % space which \verb?\shortvdotswithin{=}? takes care with for us.
 %
@@ -1842,7 +1904,7 @@ colorlinks,
 %  \cs{shortintertext} and \cs{intertext}.  \tsxPosting{Tobias Weh
 %    \\(referring to a suggestion by Chung-chieh Shan)}{2011/05/29}
 % It can be illustrated using the following example, an interested
-% reader, can apply it with and without the original \cs{intertext}
+% reader can apply it with and without the original \cs{intertext}
 % and \cs{shortintertext}.
 % \begin{verbatim}
 % % the original \intertext and \shortintertext
@@ -1859,8 +1921,8 @@ colorlinks,
 % \myline
 % \end{verbatim}
 %
-%  We now fix this internaly for both \cs{intertext} and
-%  \cs{shortintertext}, plus we add the possibility to fine tune
+%  We now fix this internally for both \cs{intertext} and
+%  \cs{shortintertext}, plus we add the possibility to fine-tune
 %  spacing around these constructions. The original versions can be
 %  brought back using the \texttt{original-x} keys below.
 %  \begin{codesyntax}
@@ -1909,7 +1971,7 @@ colorlinks,
 %    \abs{\frac{a}{b}}
 %  \]
 %  Here it won't give a nice result, so you have to manually put in
-%  either \cs{left}--\cs{right} pair or a \cs{bigl}--\cs{bigr} pair.
+%  either a \cs{left}--\cs{right} pair or a \cs{bigl}--\cs{bigr} pair.
 %  Both methods mean that you have to delete your \cs{abs} command,
 %  which may not sound like an ideal solution.
 %
@@ -1959,10 +2021,10 @@ colorlinks,
 %  \cs{DeclarePairedDelimiterX} extends the features of
 %  \cs{DeclarePairedDelimiter} such that the user will get a macro
 %  which is fenced off at either end, plus the capability to provide
-%  the \meta{body} for what ever the macro should do within these
+%  the \meta{body} for whatever the macro should do within these
 %  fences.
 %
-%  Inside the \meta{body} part, the macro \cs{delimsize} refer to the
+%  Inside the \meta{body} part, the macro \cs{delimsize} refers to the
 %  size of the outer fences. It can then be used inside \meta{body} to
 %  scale any inner fences.
 %
@@ -1990,16 +2052,16 @@ colorlinks,
 % {#1\,\delimsize\vert\,\mathopen{}#2\,\delimsize\vert\,\mathopen{}#3}
 % \end{verbatim}
 % \begin{itshape}
-%   Note the use of >>\verb|\mathopen{}|<< in the \meta{body} of
+%   Note the use of `\verb|\mathopen{}|' in the \meta{body} of
 %   \cs{braket}, this is very important when a scalable delimiter is
 %   being used and it does not present itself as a left or right
 %   delimiter. You will see why it is needed if you use
-%   \verb|\braket{A}{-B}| in a version without
+%   \verb|\braket{A}{-B}{C}| in a version without
 %   \verb|\mathopen{}|.\footnote{Basically, the problem is that
 %   \cs{vert} is a `symbol', thus $\vert-B$ is interpreted
-%   \emph{subtraction}, not a symbol followed by negative $B$. When
-%   \cs{mathopen\{\}} is added, \TeX\ is told that an opening
-%   delimiter just occurred, and it will adjust the minus
+%   \emph{subtraction}, not a symbol followed by negative $B$ (aka a
+%   sign). When \cs{mathopen\{\}} is added, \TeX\ is told that an
+%   opening delimiter just occurred, and it will adjust the minus
 %   accordingly.}
 % \end{itshape}
 %
@@ -2041,8 +2103,8 @@ colorlinks,
 % is a feature of the \cs{left}\dots\cs{right} construction).
 % \fi
 %
-% With the inner scaling, we can provide macros whos syntax closely
-% follow the mathematical meaning. Fx for building sets, try
+% With the inner scaling, we can provide macros whose syntax closely
+% follows the mathematical meaning. Fx for building sets, try
 % this\footnote{The reason for using a separate \cs{SetSymbol} macro
 % has to do with complicated set definitions, where the condition
 % spans several lines. In this case \cs{Set} cannot be used. Thus it
@@ -2082,7 +2144,7 @@ colorlinks,
 % \cs{mathchoice\{}\cs{:\}\{}\cs{:\}\{}\cs{,\}\{}\cs{,\}} instead of \cs{nonscript}\cs{:}.}
 %
 % Combining with \pkg{etoolbox} it becomes easy to make a function
-% that automatically provide a marker for a blank argument:
+% that automatically provides a marker for a blank argument:
 % \begin{verbatim}
 % \usepackage{etoolbox}
 % \DeclarePairedDelimiterX\norm[1]\lVert\rVert{
@@ -2101,7 +2163,7 @@ colorlinks,
 % \FeatureRequest{Barbara Beeton (on TSE)}{2013/10/07}
 % \cs{DeclarePairedDelimiterX} has an annoying caveat: it is very hard
 % to make a macro \verb|\lnorm{a}| that should result in $\lVert
-% a\rVert_2$.\footnote{The added >>\texttt{\_2}<< is hard to get around
+% a\rVert_2$.\footnote{The added `\texttt{\_2}' is hard to get around
 % the argument parsing.} 
 %
 % As a consequence we provide
@@ -2128,14 +2190,14 @@ colorlinks,
 % \end{verbatim}
 % Thus giving support for \verb|\Prob{A \given B}|.
 % 
-% \medskip\noindent\textbf{Note 1:} As the number of arguments increase
+% \medskip\noindent\textbf{Note 1:} As the number of arguments increases
 % the \cs{DeclarePairedDelimiter...} macros become hard for users to
 % understand. A key-value interface would be better. This is planed
 % for a future release. In
 % \url{http://tex.stackexchange.com/a/136767/3929} there is a
 % suggested replacement for \cs{DeclarePairedDelimiter}, that greatly
 % reduces the number of macros and provides a key-val
-% interface. However, the code use \pkg{xparse}, and if we want to use
+% interface. However, the code uses \pkg{xparse}, and if we want to use
 % \pkg{xparse} for some of our macros, we might just as well rewrite
 % the entire \pkg{mathtools} package in \pkg{expl3}. Also it is not
 % obvious how to get \pkg{xparse} to support \verb|[3]| for the number
@@ -2143,7 +2205,7 @@ colorlinks,
 %
 % \medskip\noindent\textbf{Note 2:} If you want to define your own
 % manual scaler macros, it is important that you besides \cs{foo} also
-% defines \cs{fool} and \cs{foor}. When a scaler is specified, in say
+% define \cs{fool} and \cs{foor}. When a scaler is specified, in say
 % \cs{abs[\cs{big}]}\marg{arg}, we actually use \cs{bigl} and
 % \cs{bigr}.
 %
@@ -2155,7 +2217,7 @@ colorlinks,
 %  auto scaled \cs{left} and \cs{right} fences behave as opening and
 %  closing fences, i.e.\ $\sin(x)$ vs. $\sin\left(x\right)$ (the later
 %  made via \verb|$\sin\left(x\right)$|), notice the gap between
-%  '$\sin$' and '('.  In some special cases it may be useful to be
+%  `$\sin$' and `('.  In some special cases it may be useful to be
 %  able to tinker with the behavior.
 %  \begin{codesyntax}
 %    \SpecialUsageIndex{\reDeclarePairedDelimiterInnerWrapper}
@@ -2176,7 +2238,7 @@ colorlinks,
 % \reDeclarePairedDelimiterInnerWrapper\abs{nostarnonscaled}{\mathinner{#1#2#3}}
 % \reDeclarePairedDelimiterInnerWrapper\abs{nostarscaled}{\mathinner{#1#2#3}}
 % \end{verbatim}
-%  The default values for the call backs corresponds to
+%  The default values for the call backs correspond to
 % \begin{verbatim}
 % star:            \mathopen{}\mathclose\bgroup #1#2\aftergroup\egroup #3
 % nostarnonscaled: \mathopen#1#2\mathclose#3
@@ -2205,7 +2267,7 @@ colorlinks,
 %  construction. Currently, this can only be applied to macros made
 %  using \cs{DeclarePairedDelimiter} and \emph{not} macros made using
 %  \cs{DeclarePairedDelimiterX} or \cs{DeclarePairedDelimiterXPP} as
-%  the contents is typeset inside a group (to limit \cs{delimsize})
+%  the contents are typeset inside a group (to limit \cs{delimsize})
 %  and thus hide any \verb|&| or \verb|\\| from \env{align} and
 %  \env{align} breaks down.
 %
@@ -2300,7 +2362,7 @@ colorlinks,
 %  the equal sign, leading to an odd-looking output. The command
 %  \cs{vcentcolon} is a shorthand for such a vertically centered
 %  colon, and can be used as in |$a \vcentcolon= b$| and results in
-%  the desired output:  $a \vcentcolon= b$. % for now
+%  the desired output:  $a \vcentcolon= b$.
 %  See also the \pkg{colonequals} package.
 %
 %  Typing \cs{vcentcolon} every time is quite tedious, so one can use
@@ -2341,11 +2403,11 @@ colorlinks,
 %    \SpecialUsageIndex{\Colonsim}\cs{Colonsim}\\
 %    \SpecialUsageIndex{\dblcolon}\cs{dblcolon}
 %  \end{codesyntax}
-%  The font packages \pkg{txfonts} and \pkg{pxfonts} provides various
+%  The font packages \pkg{txfonts} and \pkg{pxfonts} provide various
 %  symbols that include a vertically centered colon but with tighter
 %  spacing. For example, the combination |:=| exists as the symbol
 %  \cs{coloneqq} which typesets as $\coloneqq$ instead of
-%  $\vcentcolon=$. The primary disadvantage of using these fonts are
+%  $\vcentcolon=$. The primary disadvantage of using these fonts is
 %  the support packages' lack of support for \pkg{amsmath} (and thus
 %  \pkg{mathtools}) and worse yet, the side-bearings are way too
 %  tight; see~\cite{A-W:MG04} for examples. If you're not using these
@@ -2375,11 +2437,11 @@ colorlinks,
 %  \end{codesyntax}
 %
 %  \noindent
-%  \textbf{Note:} that these symbols are constructed via
+%  \textbf{Note:} These symbols are constructed via
 %  features from the \pkg{graphicx} package, and thus may not display
 %  correctly in most DVI previewers. Also note that \cs{nuparrow} and
 %  \cs{ndownarrow} are constructed via \cs{nrightarrow} and
-%  \cs{nleftarrrow} respectively, so these needs to be
+%  \cs{nleftarrrow} respectively, so these need to be
 %  present. Usually this is done via \pkg{amssymb}, but some packages
 %  may be incompatible with \pkg{amssymb} so the user will have to
 %  load \pkg{amssymb} or a similar package, that provides
@@ -2442,15 +2504,15 @@ colorlinks,
 %  \par
 %  \end{quote}
 %  \noindent
-%  As of 2013, \cs(\cs) are robust, as is the italic corrected versions.
+%  As of 2013, \cs(\cs) are robust, as are the italic corrected versions.
 %
 %  \medskip\noindent \textbf{Caveat:} Italic correction is a
 %  treacherous area. For example any penalties will cancel the italic
 %  correction inserted by
 %  \verb|\(| (for an explanation see \cite{TBT}, section 4.3.3). We
-%  have changed Michaels original to accommodate one specific penalty
+%  have changed Michael's original to accommodate one specific penalty
 %  construction: the \emph{tie}, i.e.,
-%  >>\verb|text~\(|<< will work as expected (as~of July, 2014).
+%  `\verb|text~\(|' will work as expected (as~of July, 2014).
 %
 %  \subsection{Left sub/superscripts}
 %
@@ -2692,7 +2754,7 @@ colorlinks,
 % \medskip\noindent \textbf{Note:} If you try to nest \cs{splitfrac}
 % inside each other you may need to add \cs{mathstrut} to the first
 % argument of the nested fraction to get the spacing look even. It is
-% not added by default as often a more cramped looked is desired:
+% not added by default as often a more cramped look is desired:
 % \begin{verbatim}
 %  \[
 %  \frac{
@@ -2748,9 +2810,9 @@ colorlinks,
 %  \FeatureRequest{Frank Mittelbach}{2020} In typography we use
 %  \emph{struts} to ensure specific line spacing. In text we have the
 %  \cs{strut} and in math \cs{mathstrut}. Both have no width, but
-%  equals the height and depth of an »(« from the current text/math
+%  equal the height and depth of an »(« from the current text/math
 %  font and size.  In math we often need to make minute adjustments in
-%  macro definitiones etc. The \emph{extended} math strut
+%  macro definitions etc. The \emph{extended} math strut
 %  \cs{xmathstrut} allows to \emph{increase} (decrease if negative)
 %  the math strut in two ways.
 %
@@ -2759,7 +2821,7 @@ colorlinks,
 %      \verb|\xmathstrut{0.1}| 
 %  \end{center}
 %  will give you a new strut where 10\% of the \emph{total height of
-%  the normal math stut} (\verb|\mathstrut=\xmathstrut{0}|) will be
+%  the normal math strut} (\verb|\mathstrut=\xmathstrut{0}|) will be
 %  added to both \emph{the height} and \emph{the depth} of the
 %  original strut (thus 20\% gets added in total). On the other hand
 %  \begin{center}
@@ -2809,6 +2871,7 @@ colorlinks,
 %   \llap{\rlap{\rule{18mm}{0.1pt}}\quad}a \vfb{\mathstrut} \ \vfb{\xmathstrut{0}}\
 %   \vfb{\xmathstrut{0.5} } \  \vfb{\xmathstrut{-0.1} }\  \vfb{\xmathstrut[0.5]{0}} a
 % \]
+% \newpage
 % \begin{verbatim}
 % \newcommand\vfb[1]{\begingroup\fboxsep=0pt\boxed{\,#1\,}\endgroup}
 % \[
@@ -2983,7 +3046,7 @@ colorlinks,
 %    \begin{macrocode}
 %<*package>
 \ProvidesPackage{mathtools}%
-  [2021/04/12 v1.27 mathematical typesetting tools]
+  [2021/02/02 v1.28 mathematical typesetting tools]
 %    \end{macrocode}
 % \changes{v1.10}{2011/02/12}{Might as well make sure that we need the
 % latest version of \texttt{mhsetup}}
@@ -2996,14 +3059,17 @@ colorlinks,
 % We'd like to make \cs{(}\cs{)} and \cs{[}\cs{]} robust. This can
 % easily be done via the \pkg{fixltx2e} package, but auto loading that
 % package may cause problems for some. We make copies instead.
+% Update 2021: We have removed robustifying \cs{(}\cs{)}\cs{[}\cs{]}
+% as this is now in the \LaTeX\ kernel. We still use
+% \verb|\EQ_MakeRobust| elsewhere though.
 % \begin{macro}{\EQ_MakeRobust}
 % \begin{macro}{\forced_EQ_MakeRobust}
 %    \begin{macrocode}
  % borrowed from fixltx2e
 \def\EQ_MakeRobust#1{%
   \@ifundefined{\expandafter\@gobble\string#1}{%
-    \@latex@error{The control sequence `\string#1' is undefined!%
-      \MessageBreak There is nothing here to make robust}%
+    \@latex@error{The~control~sequence~`\string#1'~is~undefined!%
+      \MessageBreak There~is~nothing~here~to~make~robust}%
     \@eha
   }%
   {%
@@ -3021,7 +3087,7 @@ colorlinks,
         \noexpand\protect\expandafter\noexpand
         \csname\expandafter\@gobble\string#1\space\endcsname}%
     }%
-    {\@latex@info{The control sequence `\string#1' is already robust}}%
+    {\@latex@info{The~control~sequence~`\string#1'~is~already~robust}}%
    }%
 }
 %    \end{macrocode}
@@ -3030,8 +3096,8 @@ colorlinks,
 %    \begin{macrocode}
 \def\forced_EQ_MakeRobust#1{%
   \@ifundefined{\expandafter\@gobble\string#1}{%
-    \@latex@error{The control sequence `\string#1' is undefined!%
-      \MessageBreak There is nothing here to make robust}%
+    \@latex@error{The~control~sequence~`\string#1'~is~undefined!%
+      \MessageBreak There~is~nothing~here~to~make~robust}%
     \@eha
   }%
   {%
@@ -3129,18 +3195,20 @@ colorlinks,
 }
 %    \end{macrocode}
 %  \end{macro}
-% \changes{v1.13}{2013/02/11}{Make \cs{(}\cs{)} and \cs{[}\cs{]}
-% robust}
-% We start of with making \cs{(}\cs{)} and \cs{[}\cs{]} robust,
-% unless the user explicitly asked us not to.
-%    \begin{macrocode}
-\MH_if_boolean:nT {robustify}{
-  \EQ_MakeRobust\(
-  \EQ_MakeRobust\)
-  \EQ_MakeRobust\[
-  \EQ_MakeRobust\]
-}
-%    \end{macrocode}
+% ^^A \changes{v1.13}{2013/02/11}{Make \cs{(}\cs{)} and \cs{[}\cs{]}
+% ^^A robust}
+% ^^A We start of with making \cs{(}\cs{)} and \cs{[}\cs{]} robust,
+% ^^A unless the user explicitly asked us not to.
+% ^^A \changes{v1.28}{2021/12/31}{Removed robustifying \cs{(}\cs{)} and
+% ^^A \cs{[}\cs{]} as this is now in the \LaTeX{} kernel.}
+% ^^A %    \begin{macrocode}
+% ^^A \MH_if_boolean:nT {robustify}{
+% ^^A  \EQ_MakeRobust\(
+% ^^A  \EQ_MakeRobust\)
+% ^^A  \EQ_MakeRobust\[
+% ^^A  \EQ_MakeRobust\]
+% ^^A }
+% ^^A %    \end{macrocode}
 %
 %
 %  \section{Macros I got ideas for myself}
@@ -3541,6 +3609,8 @@ colorlinks,
 % \changes{v1.24}{2020/03/13}{Added spaces to move the argument away
 % from the arrow head in \cs{xLeftarrow}, \cs{xRightarrow} and
 % \cs{xLeftrightarrow}. Suggested by FM}
+% \changes{1.28}{2022/01/01}{Added \cs{xlongrightarrow} and
+% \cs{xlongleftarrow} as suggested in Issue \#12}
 %    \begin{macrocode}
 \providecommand*\xleftrightarrow[2][]{%
   \ext@arrow 3095\MT_leftrightarrow_fill:{#1}{#2}}
@@ -3578,6 +3648,13 @@ colorlinks,
   \arrowfill@\leftharpoondown\relbar\relbar}
 \def\MT_leftharpoonup_fill:{%
   \arrowfill@\leftharpoonup\relbar\relbar}
+%    \end{macrocode}
+% 2022: added \verb+_fill:+ macros based upon \cs{longrightarrow} and \cs{longleftarrow}
+%    \begin{macrocode}
+\def\MT_longrightarrow_fill:{%
+  \arrowfill@\relbar\relbar\longrightarrow}
+\def\MT_longleftarrow_fill:{%
+  \arrowfill@\longleftarrow\relbar\relbar}
 \providecommand*\xrightharpoondown[2][]{%
   \ext@arrow 0359\MT_rightharpoondown_fill:{#1}{#2}}
 \providecommand*\xrightharpoonup[2][]{%
@@ -3599,6 +3676,14 @@ colorlinks,
     $\ext@arrow 3095\MT_leftharpoondown_fill:{#1}{\phantom{#2}}$}%
   \kern-\wd0 \lower.22ex\box0}}
 %    \end{macrocode}
+% 2022: added \verb+\xlong...+ macros based upon \cs{longrightarrow}
+% and \cs{longleftarrow}
+%    \begin{macrocode}
+\providecommand*\xlongrightarrow[2][]{%
+  \ext@arrow 0359\MT_longrightarrow_fill:{#1}{#2}}
+\providecommand*\xlongleftarrow[2][]{%
+  \ext@arrow 3095\MT_longleftarrow_fill:{#1}{#2}}
+%    \end{macrocode}
 %  \end{macro}
 %  \end{macro}
 %  \end{macro}
@@ -5349,12 +5434,55 @@ colorlinks,
 \def\@Aboxed#1&#2&#3\ENDDNE{%
   \ifnum0=`{}\fi \setbox \z@
     \hbox{$\displaystyle#1{}\m@th$\kern\fboxsep \kern\fboxrule }%
-    \edef\@tempa {\kern  \wd\z@ &\kern -\the\wd\z@ \fboxsep
-        \the\fboxsep \fboxrule \the\fboxrule }\@tempa \boxed {#1#2}%
+    \edef\@tempa {\kern  \wd\z@ &\kern -\the\wd\z@ 
+%    \end{macrocode}
+% The \verb|\fboxsep\the\fboxsep...| line ensures that you can use
+% \verb|\fboxsep=10pt\Aboxed{...}| in a pinch.
+%    \begin{macrocode}
+     \fboxsep\the\fboxsep \fboxrule \the\fboxrule }\@tempa \boxed {#1#2}%
 } 
 %    \end{macrocode}
 % \end{macro}
 %
+% \begin{macro}{\MakeAboxedCommand}
+%   \changes{1.28}{2022/01/01}{Added}
+% At times users want macros equivalent to \cs{Aboxed} but with a
+% different box as the base. So we provide one
+%    \begin{macrocode}
+\newcommand\MakeAboxedCommand[2]{
+  % #1: command to create
+  % #2: box command to use
+  \newcommand#1[1]{\let\bgroup{\romannumeral-`}%
+    \@nameuse{@@\MH_cs_to_str:N #1}##1&&\ENDDNE}
+  \@namedef{@@\MH_cs_to_str:N #1}##1&##2&##3\ENDDNE{%
+%    \end{macrocode}
+% Instead of hardcoding the kerning of box rule and box sep, we record
+% the width of an empty box and kern half of it.
+%    \begin{macrocode}
+    \settowidth\@tempdimc{#2{}}%
+    \ifnum0=`{}\fi \setbox \z@
+    \hbox{$\displaystyle##1{}\m@th$\kern0.5\@tempdimc}%
+%    \end{macrocode}
+% The \verb|\fboxsep\the\fboxsep...| line enables
+% \verb|\fboxsep=10\Command{...&...}|. Of course only works for boxed
+% that uses \cs{fboxsep} and \cs{fboxrule}.
+%    \begin{macrocode}
+    \edef\@tempa{\kern\wd\z@&\kern-\the\wd\z@%
+       \fboxsep\the\fboxsep \fboxrule \the\fboxrule}%
+    \@tempa%
+%    \end{macrocode}
+% Instead of using \cs{boxed} directly, we mimick the definition of
+% \cs{boxed} and should thus be able to use any box.
+%    \begin{macrocode}
+    #2{\m@th$\displaystyle ##1##2$}%  
+  }
+}
+
+%    \end{macrocode}
+% 
+% \end{macro}
+%
+%
 % \begin{macro}{\ArrowBetweenLines}
 %   \changes{v1.05}{2008/06/05}{Added \cs{ArrowBetweenLines} as it
 %   belongs here and not just in my \LaTeX book (daleif)}
diff --git a/Master/texmf-dist/source/latex/mathtools/mathtools.ins b/Master/texmf-dist/source/latex/mathtools/mathtools.ins
index dbc22bd44e7..81a5ef50c2a 100644
--- a/Master/texmf-dist/source/latex/mathtools/mathtools.ins
+++ b/Master/texmf-dist/source/latex/mathtools/mathtools.ins
@@ -12,6 +12,7 @@
 %% Copyright (C) 2012-2019 by Lars Madsen
 %% Copyright (C) 2020-     by Lars Madsen, the LaTeX3 project
 %% 
+%% 
 %% This work may be distributed and/or modified under the
 %% conditions of the LaTeX Project Public License, either
 %% version 1.3c of this license or (at your option) any later
diff --git a/Master/texmf-dist/source/latex/mathtools/mhsetup.dtx b/Master/texmf-dist/source/latex/mathtools/mhsetup.dtx
index bf89bc9c887..8d967baf87a 100644
--- a/Master/texmf-dist/source/latex/mathtools/mhsetup.dtx
+++ b/Master/texmf-dist/source/latex/mathtools/mhsetup.dtx
@@ -190,7 +190,7 @@ and the derived files
 %  \cs{InternalSyntaxOn} which makes |_| and |:| letters and then
 %  automatically restores the category codes at the end of the
 %  package. This usually works fine but when you try to load
-%  \pkg{amstext} you will experience that \TeX{} goes into an
+%  \pkg{\mbox{amstext}} you will experience that \TeX{} goes into an
 %  infinite loop. Packages containing code like
 %  |\@for\@tempa:=\@tempb\do{...}| will not work correctly either,
 %  thus we provide an alternative version here with the pair of
@@ -207,7 +207,7 @@ and the derived files
 %  The standard behavior of scanning for optional arguments in
 %  \LaTeX{} allows any number of spaces preceding the optional
 %  argument and that is not always good in math. For that reason
-%  \pkg{amsmath} makes sure that commands like |\\| disallows spaces
+%  \pkg{amsmath} makes sure that commands like |\\| disallow spaces
 %  before the optional argument but at the same time it fails to
 %  provide ``safe'' environments. What would you expect from the
 %  following input?
@@ -338,7 +338,7 @@ and the derived files
 %  The whole idea is to provide programming tools that are convenient
 %  but not yet widely available. I hope this'll be obsolete soon!
 %
-%  Firstly we setup a few helper functions.
+%  Firstly we set up a few helper functions.
 %  \begin{macro}{\MH_let:NwN}
 %  An alias for \cs{let}.
 %    \begin{macrocode}
@@ -354,8 +354,8 @@ and the derived files
 %    \end{macrocode}
 %  \end{macro}
 %  \begin{macro}{\MH_let:cc}
-%  This one has takes a \cs{csname}-\cs{endcsname} name and \cs{let}s
-%  it to a another \cs{csname}-\cs{endcsname} name. To be used in
+%  This one takes a \cs{csname}-\cs{endcsname} name and \cs{let}s
+%  it to another \cs{csname}-\cs{endcsname} name. To be used in
 %  constructions with weird characters like \texttt{*} or alike in
 %  them and can take a \cs{global} prefix if wanted (we want that
 %  later on).
diff --git a/Master/texmf-dist/source/latex/mathtools/mhsetup.ins b/Master/texmf-dist/source/latex/mathtools/mhsetup.ins
new file mode 100644
index 00000000000..edf6baa8244
--- /dev/null
+++ b/Master/texmf-dist/source/latex/mathtools/mhsetup.ins
@@ -0,0 +1,93 @@
+%%
+%% This is file `mhsetup.ins',
+%% generated with the docstrip utility.
+%%
+%% The original source files were:
+%%
+%% mhsetup.dtx  (with options: `install')
+%% 
+%% This is a generated file.
+%% 
+%% Copyright (C) 2002-2007,2010 by Morten Hoegholm
+%% Copyright (C) 2017-2019      by Lars Madsen
+%% Copyright (C) 2020-          by Lars Madsen, The LaTeX3 team
+%% 
+%% 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".
+%% 
+%% This Current Maintainer of this work is Lars Madsen
+%% <daleif@math.au.dk>, The LaTeX3 team https://github.com/latex3/mathtools
+%% 
+%% This work consists of the main source file mhsetup.dtx
+%% and the derived files
+%%    mhsetup.sty, mhsetup.pdf, mhsetup.ins, mhsetup.drv.
+%% 
+\input docstrip.tex
+\Msg{************************************************************************}
+\Msg{* Installation}
+\Msg{* Package: mhsetup 2017/03/31 v1.3 mhsetup}
+\Msg{************************************************************************}
+
+\keepsilent
+\askforoverwritefalse
+
+\preamble
+
+This is a generated file.
+
+Copyright (C) 2002-2007,2010 by Morten Hoegholm
+Copyright (C) 2017-2019      by Lars Madsen
+Copyright (C) 2020-          by Lars Madsen, The LaTeX3 team
+
+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".
+
+This Current Maintainer of this work is Lars Madsen
+<daleif@math.au.dk>, The LaTeX3 team https://github.com/latex3/mathtools
+
+This work consists of the main source file mhsetup.dtx
+and the derived files
+   mhsetup.sty, mhsetup.pdf, mhsetup.ins, mhsetup.drv.
+
+\endpreamble
+
+\generate{%
+  \file{mhsetup.ins}{\from{mhsetup.dtx}{install}}%
+  \file{mhsetup.drv}{\from{mhsetup.dtx}{driver}}%
+  \usedir{tex/latex/mh}%
+  \file{mhsetup.sty}{\from{mhsetup.dtx}{package}}%
+}
+
+\obeyspaces
+\Msg{************************************************************************}
+\Msg{*}
+\Msg{* To finish the installation you have to move the following}
+\Msg{* file into a directory searched by TeX:}
+\Msg{*}
+\Msg{*     mhsetup.sty}
+\Msg{*}
+\Msg{* To produce the documentation run the file `mhsetup.drv'}
+\Msg{* through LaTeX.}
+\Msg{*}
+\Msg{* Happy TeXing!}
+\Msg{*}
+\Msg{************************************************************************}
+
+\endbatchfile
+\endinput
+%%
+%% End of file `mhsetup.ins'.