%D \module
%D   [       file=math-frc,
%D        version=2007.07.19,
%D          title=\CONTEXT\ Math Macros,
%D       subtitle=Fractions,
%D         author={Hans Hagen \& Taco Hoekwater},
%D           date=\currentdate,
%D      copyright=\PRAGMA]
%C
%C This module is part of the \CONTEXT\ macro||package and is
%C therefore copyrighted by \PRAGMA. See mreadme.pdf for
%C details.

\writestatus{loading}{ConTeXt Math Macros / Fractions}

\unprotect

%D \macros
%D   {frac, xfrac, xxfrac}
%D
%D This is another one Tobias asked for. It replaces the
%D primitive \type {\over}. We also take the opportunity to
%D handle math style restoring, which makes sure units and
%D chemicals come out ok.
%D The \type {\frac} macro kind of replaces the awkward \type
%D {\over} primitive. Say that we have the following formulas:
%D
%D \startbuffer[sample]
%D test $\frac  {1}{2}$ test $$1 + \frac  {1}{2} = 1.5$$
%D test $\xfrac {1}{2}$ test $$1 + \xfrac {1}{2} = 1.5$$
%D test $\xxfrac{1}{2}$ test $$1 + \xxfrac{1}{2} = 1.5$$
%D \stopbuffer
%D
%D \typebuffer[sample]
%D
%D With the most straightforward definitions, we get:
%D
%D \startbuffer[code]
%D \def\dofrac#1#2#3{\relax\mathematics{{{#1{#2}}\over{#1{#3}}}}}
%D
%D \def\frac  {\dofrac\mathstyle}
%D \def\xfrac {\dofrac\scriptstyle}
%D \def\xxfrac{\dofrac\scriptscriptstyle}
%D \stopbuffer
%D
%D \typebuffer[code] \getbuffer[code,sample]
%D
%D Since this does not work well, we can try:
%D
%D \startbuffer[code]
%D \def\xfrac #1#2{\hbox{$\dofrac\scriptstyle      {#1}{#2}$}}
%D \def\xxfrac#1#2{\hbox{$\dofrac\scriptscriptstyle{#1}{#2}$}}
%D \stopbuffer
%D
%D \typebuffer[code] \getbuffer[code,sample]
%D
%D This for sure looks better than:
%D
%D \startbuffer[code]
%D \def\xfrac #1#2{{\scriptstyle      \dofrac\relax{#1}{#2}}}
%D \def\xxfrac#1#2{{\scriptscriptstyle\dofrac\relax{#1}{#2}}}
%D \stopbuffer
%D
%D \typebuffer[code] \getbuffer[code,sample]
%D
%D So we stick to the next definitions (watch the local
%D overloading of \type {\xfrac}).

% \def\dofrac#1#2#3{\relax\mathematics{{{#1{#2}}\over{#1{#3}}}}}

\def\dofrac#1#2#3{\relax\mathematics{\Ustack{{#1{#2}}\normalover{#1{#3}}}}}
\def\nofrac  #1#2{\relax\mathematics{\Ustack{{#1}\normalover{#2}}}}

% \chardef\mathfracmode=0 $\frac{1}{2}$
% \chardef\mathfracmode=1 $\frac{1}{2}$
% \chardef\mathfracmode=2 $\frac{1}{2}$
% \chardef\mathfracmode=3 $\frac{1}{2}$
% \chardef\mathfracmode=4 $\frac{1}{2}$
% \chardef\mathfracmode=5 $\frac{1}{2}$

\chardef\mathfracmode=0 % 0=auto, 1=displaystyle, 2=textstyle, 3=scriptstyle, 4=scriptscriptstyle, 5=mathstyle

\unexpanded\def\frac
  {\ifcase\mathfracmode
     \expandafter\nofrac
   \or
     \expandafter\dofrac\expandafter\displaystyle
   \or
     \expandafter\dofrac\expandafter\textstyle
   \or
     \expandafter\dofrac\expandafter\scriptstyle
   \or
     \expandafter\dofrac\expandafter\scriptscriptstyle
   \else
     \expandafter\dofrac\expandafter\mathstyle
   \fi}

\unexpanded\def\xfrac#1#2%
  {\begingroup
   \let\xfrac\xxfrac
   \dofrac\scriptstyle{#1}{#2}%
   \endgroup}

\unexpanded\def\xxfrac#1#2%
  {\begingroup
   \dofrac\scriptscriptstyle{#1}{#2}%
   \endgroup}

%D The \type {xx} variant looks still ugly, so maybe it's
%D best to say:

\unexpanded\def\xxfrac#1#2%
  {\begingroup
   \dofrac\scriptscriptstyle{#1}{\raise.25ex\hbox{$\scriptscriptstyle#2$}}%
   \endgroup}

%D Something low level for scientific calculator notation:

\unexpanded\def\scinot#1#2%
  {#1\times10^{#2}}

%D The next macro, \type {\ch}, is \PPCHTEX\ aware. In
%D formulas one can therefore best use \type {\ch} instead of
%D \type {\chemical}, especially in fractions.

% let's see who complains ... \mathstyle is now a primitive
%
% \unexpanded\def\ch#1%
%   {\ifdefined\@@chemicalletter
%      \dosetsubscripts
%      \mathstyle{\@@chemicalletter{#1}}%
%      \doresetsubscripts
%    \else
%      \mathstyle{\rm#1}%
%    \fi}

% \unexpanded\def\ch#1%
%   {\ifdefined\@@chemicalletter
%      \dosetsubscripts
%      \mathematics{\@@chemicalletter{#1}}%
%      \doresetsubscripts
%    \else
%      \mathematics{\rm#1}%
%    \fi}

%D \macros
%D   {/}
%D
%D Just to be sure, we restore the behavior of some typical
%D math characters.

\bgroup

\catcode`\/=\@@other    \global           \let\normalforwardslash/
\catcode`\/=\@@active \doglobal\appendtoks\let/\normalforwardslash\to\everymathematics

\egroup

% to be checked:

\def\exmthfont#1{\symbolicsizedfont#1\plusone{MathExtension}}

\def\domthfrac#1#2#3#4#5#6#7%
  {\begingroup
   \mathsurround\zeropoint
   \setbox0\hbox{$#1 #6$}%
   \setbox2\hbox{$#1 #7$}%
   \dimen0\wd0
   \ifdim\wd2>\dimen0 \dimen0\wd2 \fi
   \setbox4\hbox to \dimen0{\exmthfont#2#3\leaders\hbox{#4}\hss#5}%
   \mathord{\vcenter{{\offinterlineskip
     \hbox to \dimen0{\hss\box0\hss}%
     \kern \ht4%
     \hbox to \dimen0{\hss\copy4\hss}%
     \kern \ht4%
     \hbox to \dimen0{\hss\box2\hss}}}}%
   \endgroup}

\def\domthsqrt#1#2#3#4#5%
  {\begingroup
   \mathsurround\zeropoint
   \setbox0\hbox{$#1 #5$}%
   \dimen0=1.05\ht0 \advance\dimen0 1pt  \ht0 \dimen0
   \dimen0=1.05\dp0 \advance\dimen0 1pt  \dp0 \dimen0
   \dimen0\wd0
   \setbox4\hbox to \dimen0{\exmthfont#2\leaders\hbox{#3}\hfill#4}%
   \delimitershortfall=0pt
   \nulldelimiterspace=0pt
   \setbox2\hbox{$\left\delimiter"0270370 \vrule height\ht0 depth \dp0 width0pt
                  \right.$}%
   \mathord{\vcenter{\hbox{\copy2
                           \rlap{\raise\dimexpr\ht2-\ht4\relax\copy4}\copy0}}}%
   \endgroup}

\def\mthfrac#1#2#3#4#5{\mathchoice
  {\domthfrac\displaystyle     \textface        {#1}{#2}{#3}{#4}{#5}}
  {\domthfrac\textstyle        \textface        {#1}{#2}{#3}{#4}{#5}}
  {\domthfrac\scriptstyle      \scriptface      {#1}{#2}{#3}{#4}{#5}}
  {\domthfrac\scriptscriptstyle\scriptscriptface{#1}{#2}{#3}{#4}{#5}}}

\def\mthsqrt#1#2#3{\mathchoice
  {\domthsqrt\displaystyle     \textface    {#1}{#2}{#3}}
  {\domthsqrt\textstyle        \textface    {#1}{#2}{#3}}
  {\domthsqrt\scriptstyle      \textface    {#1}{#2}{#3}}
  {\domthsqrt\scriptscriptstyle\textface    {#1}{#2}{#3}}}

% temp here

\protect \endinput