با سلام
چگونه میتوان دستور فلش نقطه چین از بالا به پایین به صورت عمودی نوشت به طوریکه در دو طرف بالا و پایین حرف و در کنار فلش (طوری که روی آن باشد) حرف باشد.
\documentclass[10pt]{amsart}
% Setup Environments
\makeatletter
\newcommand{\da@rightarrow}{\mathchar"0\hexnumber@\symAMSa 4B }
\newcommand{\da@leftarrow}{\mathchar"0\hexnumber@\symAMSa 4C }
\newcommand{\da@downarrow}{\mathchar"0\hexnumber@\symAMSa 4D }
\newcommand{\xdashrightarrow}[2][]{%
\mathrel{%
\mathpalette{\da@xarrow{#1}{#2}{}\da@rightarrow{\,}{}}{}%
}%
}
\newcommand{\xdashleftarrow}[2][]{%
\mathrel{%
\mathpalette{\da@xarrow{#1}{#2}\da@leftarrow{}{}{\,}}{}%
}%
}
\newcommand{\xdashdownarrow}[2][]{%
\mathrel{%
\mathpalette{\da@xarrow{#1}{#2}{}\da@downarrow{\,}{}}{}%
}%
}
\newcommand{\da@xarrow}[7]{%
% #1: below
% #2: above
% #3: arrow left
% #4: arrow right
% #5: space left
% #6: space right
% #7: math style
\sbox0{$\ifx#7\scriptstyle\scriptscriptstyle\else\scriptstyle\fi#5#1#6\m@th$}%
\sbox2{$\ifx#7\scriptstyle\scriptscriptstyle\else\scriptstyle\fi#5#2#6\m@th$}%
\sbox4{$#7\dabar@\m@th$}%
\dimen@=\wd0 %
\ifdim\wd2 >\dimen@
\dimen@=\wd2 %
\fi
\count@=2 %
\def\da@bars{\dabar@\dabar@}%
\@whiledim\count@\wd4<\dimen@\do{%
\advance\count@\@ne
\expandafter\def\expandafter\da@bars\expandafter{%
\da@bars
\dabar@
}%
}%
\mathrel{#3}%
\mathrel{%
\mathop{\da@bars}\limits
\ifx\#1\%
\else
_{\copy0}%
\fi
\ifx\#2\%
\else
^{\copy2}%
\fi
}%
\mathrel{#4}%
}
\makeatother
\begin{document}
\begin{proof}
[\begin{array}{*{20}{c}}
{}&{}&{}&{}&0&{}&0&{}&{}\
{}&{}&{}&{}& \downarrow &{}& \downarrow &{}&{}\
0& \to &X&{\xrightarrow{{h}}}&Y&{\xrightarrow{{g}}}&X& \to &0\
{}&{}&{}&{}&{{ \downarrow ^f}}&{}&{\xdashdownarrow {^\alpha }}&{}&{}\
{}&{}&{}&{}&{{Y}}&{ \xdashrightarrow{{\alpha}}
}&Y&{}&{}\
{}&{}&{}&{}& \downarrow &{}&{}&{}&{}\
{}&{}&{}&{}&{Y'}&{}&{}&{}&{}\
{}&{}&{}&{}& \downarrow &{}&{}&{}&{}\
{}&{}&{}&{}&0&{}&{}&{}&{}
\end{array}]
\end{proof}
\end{document}
ویرایش
