% Push:  in tabular and array env, add
% push command for pushing up \hlines
% set in tabular and array environments.
%    \push  -- push up (for superscripts)
%    \dpush -- push down (subscripts)
%    \apush -- push in both directions.
%    \rowspan -- move text down 1/2 line.
% Richard Hughey 23 Jan 1991
\def\@@pushline#1{{%
\setbox3\hbox{#1}\dimen3=\ht3\advance\dimen3 3.5pt\box3\rule{0pt}{\dimen3}}}
\def\@@dpushline#1{{%
\setbox3\hbox{#1}\dimen4=\dp3\advance\dimen4 3.5pt\box3\rule[-\dimen4]{0pt}{\ht3}}}
\def\@@apushline#1{{%
\setbox3\hbox{#1}\dimen3=\ht3\advance\dimen3 7pt\dimen4=\dp3%
\advance\dimen3\dp3\advance\dimen4 3.5pt\box3\rule[-\dimen4]{0pt}{\dimen3}}}
\def\@@rowspan{\@ifnextchar[{\@@@rowspan}{\@@@rowspan[1.5ex]}}
\def\@@@rowspan[#1]#2{{\setbox1\hbox{#2}\dimen1=.5\baselineskip%
                  \advance\dimen1 #1%
                  \vbox to 0pt{\vskip\dimen1\vbox to \dp1{\vss\box1}\vss}}}
\def\@@mpushline#1{\@@pushline{$#1$}}
\def\@@mdpushline#1{\@@dpushline{$#1$}}
\def\@@mmpushline#1{\mbox{\@@pushline{#1}}}
\def\@@mapushline#1{\mbox{\@@apushline{$#1$}}}
\def\@@@mrowspan[#1]#2{\@@rowspan{$#2$}}
\def\@@mrowspan{\@ifnextchar[{\@@@mrowspan}{\@@@mrowspan[1.5ex]}}
\let\@rphtabular=\tabular
\let\@rpharray=\array
\def\tabular{\let\push=\@@pushline\let\dpush=\@@dpushline%
             \let\apush=\@@apushline\let\rowspan=\@@rowspan\@rphtabular}
\def\array{\let\push=\@@mpushline\let\mpush=\@@mmpushline
           \let\rowspan=\@@mrowspan\let\mrowspan=\@@rowspan
           \let\dpush=\@@mdpushline\let\apush\@@mapushline\@rpharray}