[NTG-context] math align

[David Arnold]

And where should we put this module temporarily?


On Jan 15, 2006, at 2:37 PM, Hans Hagen wrote:

> Hi,
>
> Here a first attempts for a flexible alignment mechanism (i depend  
> on taco for the fine points of math typesetting since he's typeset  
> \infty more complex formulas than i have)
>
> (n=n_of_columns, m=n_of_pairs, so both requested multiple column  
> features are supported)
>
> Hans
>
> %D \module
> %D   [       file=math-ext,
> %D        version=2006.01.14,
> %D          title=\CONTEXT\ Math Macros,
> %D       subtitle=Extra Macros,
> %D         author=Hans Hagen,
> %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.
>
> % some simple math constructs (based on user requests)
> %
> % preliminary
>
> \unprotect
>
> % adapted stuff
>
> % we need to make this plain code a bit more 'readable'
>
> \def\openup
>   {\afterassignment\dopenup\scratchdimen=}
>
> \def\dopenup
>   {\advance\lineskip     \scratchdimen
>    \advance\baselineskip \scratchdimen
>    \advance\lineskiplimit\scratchdimen}
>
> \def\jot{.25\bodyfontsize} % plain tex: 3 pt (todo: better name)
>
> \newif\ifdt at p
>
> \def\displ at y % \presetdisplayspacing or so
>   {\global\dt at ptrue
>    \openup\jot
>    \mathsurround\zeropoint
>    \everycr{\noalign{%
>       \ifdt at p
>         \global\dt at pfalse
>         \ifdim\prevdepth>-\thousandpoint
>           \vskip-\lineskiplimit
>           \vskip\normallineskiplimit
>         \fi
>       \else
>         \penalty\interdisplaylinepenalty
>       \fi}}}
>
> % context (hooks)
>
> \let\normaldispl at y\displ at y
>
> \def\displ at y{\resetdisplaymatheq\normaldispl at y}
>
> \let\presetdisplaymath\displ at y
>
> % plain tex value: \centering = 0pt plus 1000pt minus 1000pt
> % plain tex valye: \jot = 3pt
>
> % n>1 #### needed, strange # interaction (maybe we need a toks in  
> recurse ane no macro)
>
> \def\buildeqalign
>   {\scratchtoks\emptytoks
>    \dorecurse\@@eqm
>      {\ifnum\recurselevel>\plusone\appendtoks\tabskip\@@eqdistance& 
> \tabskip\zeropoint\to\scratchtoks\fi
>       \expanded{\scratchtoks{\the\scratchtoks\the\!!toksa}}%
>       \dorecurse{\numexpr\@@eqn-\plusone\relax}
>         {\expanded{\scratchtoks{\the\scratchtoks\the\!!toksb}}}}%
>    \expanded{\scratchtoks{\the\scratchtoks\the\!!toksc}}}
>
> \def\forgetalign
>   {\tabskip\zeropoint\everycr\emptytoks}
>
> \def\eqalign#1% why no halign here, probably because of displaywidth
>   {\!!toksa{\strut\hfil$\displaystyle{##}$}%
>    \!!toksb{&$\displaystyle{{}##}$\hfil}%
>    \!!toksc\emptytoks
>    \buildeqalign
>    \null\,\vcenter
>      {\openup\jot
>       \mathsurround\zeropoint
>       \expandafter \ialign \expandafter {\the\scratchtoks\crcr#1 
> \crcr}%
>    }\,}
>
> \def\eqalignno#1%
>   {\!!toksa{\hfil$\forgetalign\displaystyle{##}$\tabskip\zeropoint}%
>    \!!toksb{&$\forgetalign\displaystyle{{}##}$\tabskip\zeropoint}%
>    \!!toksc{\hfil\tabskip\centering&\llap{$\forgetalign##$}\tabskip 
> \zeropoint}%
>    \buildeqalign
>    \presetdisplaymath
>    \tabskip\centering
>    \halign to \displaywidth \expandafter {\the\scratchtoks\crcr#1 
> \crcr}}
>
> \def\leqalignno#1%
>   {\!!toksa{\hfil$\forgetalign\displaystyle{##}$\tabskip\zeropoint}%
>    \!!toksb{&$\forgetalign\displaystyle{{}##}$\tabskip\zeropoint}%
>    \!!toksc{\hfil\tabskip\centering&\kern-\displaywidth\rlap{$ 
> \forgetalign##$}\tabskip\displaywidth}%
>    \buildeqalign
>    \presetdisplaymath
>    \tabskip\centering
>    \halign to \displaywidth \expandafter {\the\scratchtoks\crcr#1 
> \crcr}}
>
> \definesystemvariable{eq}
>
> \def\setupmathalign
>   {\dodoubleargument\getparameters[\??eq]}
>
> \setupmathalign
>   [\c!n=2,
>    \c!m=1,
>    \c!distance=1em]
>
> \def\numberedeqalign
>   {\doifelse\@@fmlocation\v!left\leqalignno\eqalignno}
>
> \def\doalignNR[#1][#2]%
>   {\doifsomething{#1}
>      {\doifelse{#1}{+}
>         {\doformulanumber[][#2][]{}}
>         {\doformulanumber[#1][#2][]{}}}}
>
> \def\startalign
>   {\dosingleempty\dostartalign}
>
> \long\def\dostartalign[#1]#2\stopalign
>   {\doifassignmentelse{#1}{\setupmathalign[#1]}\donothing
>    \def\NC{\crcr\def\NC####1{&####1}}%
>    \def\EQ{&=}
>    \def\NR{&\dodoubleempty\doalignNR}%
>    % amstex compatibility mode: (ugly)
>    \def\notag{\def\\{&\crcr}}%
>    \doifelse{#1}{*}{\def\\{&\crcr}}{\def\\{&\doalignNR[+][]\crcr}}%
>    % end of compatibility mode
>    \numberedeqalign{#2}}
>
> %D \startbuffer
> %D \placeformula \startformula \eqalignno {
> %D  a &= b & \formulanumber \cr
> %D  c &= d \cr
> %D    &= e \cr
> %D    &= f & \formulanumber
> %D } \stopformula
> %D \stopbuffer
> %D
> %D \typebuffer \getbuffer
> %D
> %D \startbuffer
> %D \placeformula \startformula \startalign
> %D \NC  a \EQ b \NR[+]
> %D \NC  c \EQ d \NR
> %D \NC    \EQ f \NR[for:hans]
> %D \NC    \EQ g \NR[for:whoelse][a]
> %D \NC    \EQ h \NR[for:whomore][b]
> %D \NC    \EQ i \NR
> %D \stopalign \stopformula
> %D \stopbuffer
> %D
> %D \typebuffer \getbuffer
> %D
> %D \startbuffer
> %D \placeformula \startformula \startalign
> %D \NC a \EQ b \NR[+]
> %D \NC c \EQ d \NR
> %D \NC   \EQ f \NR
> %D \NC   \EQ g \NR
> %D \NC   \EQ h \NR
> %D \NC   \EQ i \NR[+]
> %D \stopalign \stopformula
> %D \stopbuffer
> %D
> %D \typebuffer \getbuffer
> %D
> %D \startbuffer
> %D \placeformula \startformula \startalign
> %D a &= b \\
> %D c &= d \notag \\
> %D   &= e \notag \\
> %D   &= f \\
> %D \stopalign \stopformula
> %D \stopbuffer
> %D
> %D \typebuffer \getbuffer
> %D
> %D \startbuffer
> %D \placeformula \startformula \startalign
> %D a &= b \NR[+]
> %D c &= d \NR
> %D   &= e \NR
> %D   &= f \NR[+]
> %D \stopalign \stopformula
> %D \stopbuffer
> %D
> %D \typebuffer \getbuffer
> %D
> %D \startbuffer
> %D \placeformula \startformula \startalign
> %D \NC  a \NC \eq  b \NR[+]
> %D \NC  c \NC \neq d \NR
> %D \NC    \NC \neq f \NR[for:hans]
> %D \NC    \NC \geq g \NR[for:whoelse][a]
> %D \NC    \NC \leq h \NR[for:whomore][b]
> %D \NC    \NC \neq i \NR
> %D \stopalign \stopformula
> %D \stopbuffer
> %D
> %D \typebuffer \getbuffer
> %D
> %D \startbuffer
> %D \placeformula \startformula \startalign[*]
> %D a &= b \\
> %D c &= d \notag \\
> %D   &= e \notag \\
> %D   &= f \\
> %D \stopalign \stopformula
> %D \stopbuffer
> %D
> %D \typebuffer \getbuffer
> %D
> %D \startbuffer
> %D \placeformula \startformula \startalign
> %D     x &= y \\
> %D     a &= b \\
> %D \stopalign \stopformula
> %D \stopbuffer
> %D
> %D \typebuffer \getbuffer
> %D
> %D \startbuffer
> %D \placeformula \startformula \startalign[m=3]
> %D     x &= y & x &= y & z &= t \\
> %D     a &= b & p &= q & w &= s \\
> %D \stopalign \stopformula
> %D \stopbuffer
> %D
> %D \typebuffer \getbuffer
> %D
> %D \startbuffer
> %D \placeformula \startformula \startalign[m=3,distance=0pt]
> %D     x &= y &= x &= y &= z &= t \\
> %D     a &= b &= p &= q &= w &= s \\
> %D \stopalign \stopformula
> %D \stopbuffer
> %D
> %D \typebuffer \getbuffer
> %D
> %D \startbuffer
> %D \placeformula \startformula \startalign[n=5,distance=0pt]
> %D     x &= yy &= xx &= yy &= zz \\
> %D     a &= b  &= p  &= q  &= w  \\
> %D \stopalign \stopformula
> %D \stopbuffer
> %D
> %D \typebuffer \getbuffer
>
> \protect \endinput
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