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%D \module
%D [ file=supp-mat,
%D version=1998.09.10,
%D title=\CONTEXT\ Support Macros,
%D subtitle=Math,
%D author=Hans Hagen,
%D date=\currentdate,
%D copyright={PRAGMA / Hans Hagen \& Ton Otten}]
%C
%C This module is part of the \CONTEXT\ macro||package and is
%C therefore copyrighted by \PRAGMA. See mreadme.pdf for
%C details.
%D For practical reasons, I decided to move some math things to
%D a support module. There is nothing spectacular here.
\writestatus{loading}{Context Support Macros / Math}
\unprotect
%D \macros
%D {mathematics, math, nomathematics, startmathmode}
%D
%D The \type{$} can be both an begin and end math character.
%D This can lead to confusing and errorprone situations when
%D macros insert \type{$}. When for instance we have defined:
%D
%D \starttyping
%D \def\MyPlus{$\,+\,$}
%D \stoptyping
%D
%D the sequence \type{$x^2 \MyPlus y^2 = r^2$} will expand to:
%D
%D \starttyping
%D $x^2 $\,+\,$ y^2 = r^2$
%D \stoptyping
%D
%D Here the \type{\,} are given outside math mode and \TEX\ will
%D definitely complain about this. A more save definition would
%D have been:
%D
%D \starttyping
%D \def\MyPlus{\mathematics{\,+\,}}
%D \stoptyping
%D
%D Which is implemented as:
\def\mathematics#1{\relax\ifmmode#1\else$#1$\fi} % lookahead bug reported by brooks
\def\startmathmode
{\ifmmode
\let\stopmathmode\relax
\else
$\def\stopmathmode{$}% \let\stopmathmode=$
\fi}
\def\nomathematics#1%
{\ifmmode\hbox{#1}\else#1\fi}
\let\math\mathematics
%D \macros
%D {dimension, nodimension}
%D
%D The next few macros are used for typesetting dimensions in
%D such a way that spacing is acceptable. I won't spend much
%D words on these macros, because they will be overloaded in
%D the units module.
\newsignal\dimensionsignal
\def\dimensiontypeface {\tf}
\def\dimensionhalfspace {\,}
\unexpanded\def\dimension#1%
{\def\dodimensionsignal{\kern\dimensionsignal}%
\ifdim\lastskip=\zeropoint\relax
\ifdim\lastkern=\zeropoint\relax
\ifmmode
\mathematics{\dimensionhalfspace\dimensionhalfspace\dimensiontypeface#1}%
\else
\mathematics{\dimensiontypeface#1}%
\fi
\else\ifdim\lastkern=\dimensionsignal
\mathematics{\dimensionhalfspace\dimensiontypeface#1}%
\else
\unkern\mathematics{\dimensionhalfspace\dimensionhalfspace\dimensiontypeface#1}%
\fi\fi
\else
\unskip\mathematics{\dimensionhalfspace\dimensionhalfspace\dimensiontypeface#1}%
\fi
\dodimensionsignal}
\unexpanded\def\nodimension#1%
{\unskip#1\global\let\dodimensionsignal\relax}
%D \macros
%D {super, suber}
%D
%D \TEX\ uses \type{^} and \type{_} for entering super- and
%D subscript mode. We want however a bit more control than
%D normally provided, and therefore provide \type {\super}
%D and \type{\suber} (\type {\sub} is already taken).
\global\let\normalsuper=^
\global\let\normalsuber=_
\newcount\supersubmode
\newevery\everysupersub \EverySuperSub
\appendtoks \advance\supersubmode 1\relax \to \everysupersub
% \def\dodosuper#1{\normalsuper{\the\everysupersub#1}}
% \def\dodosuber#1{\normalsuber{\the\everysupersub#1}}
%
% \def\dosuper{\ifx\next\bgroup\expandafter\dodosuper\else\normalsuper\fi}
% \def\dosuber{\ifx\next\bgroup\expandafter\dodosuber\else\normalsuber\fi}
%
% \def\super{\futurelet\next\dosuper}
% \def\suber{\futurelet\next\dosuber}
\def\super#1{\normalsuper{\the\everysupersub#1}}
\def\suber#1{\normalsuber{\the\everysupersub#1}}
%D \macros
%D {enablesupsub}
%D
%D We can let \type {^} and \type {_} act like \type {\super}
%D and \type {\suber} by saying \type {\enablesupsub}.
\bgroup
\catcode`\^=\@@active
\catcode`\_=\@@active
\gdef\enablesupsub
{\catcode`\^=\@@active
\def^{\ifmmode\expandafter\super\else\expandafter\normalsuper\fi}%
\catcode`\_=\@@active
\def_{\ifmmode\expandafter\suber\else\expandafter\normalsuber\fi}}
\egroup
%D \macros
%D {restoremathstyle}
%D
%D We can pick up the current math style by calling \type
%D {\restoremathstyle}.
\def\restoremathstyle
{\ifmmode
\ifcase\supsubmode
\textstyle
\or
\scriptstyle
\else
\scriptscriptstyle
\fi
\fi}
\protect \endinput
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