Define a commutative diagram and reuse it

Question

In a paper I am writing, I need to to draw double complex, which is a fairly complicated commutative diagram. I wrote it using tikzcd, and the code is the following

\documentclass{article}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{tikz-cd}
\newcommand{\s}[1]{\mathscr{#1}}
\begin{document}    
\begin{tikzcd}
    & 0 \arrow{r} 
        & O_X \arrow{r}{\partial}\arrow{d}{i} 
        & \Omega^1_X \arrow{r}{\partial}\arrow{d}{i} 
        & \dots\arrow{r}{\partial}\arrow{d}{i} 
        & \Omega^n_X\arrow{r}\arrow{d}{i} 
    & 0 \\
    & 0 \arrow{r} 
        & \s{A}\arrow{r}{\partial}\arrow{d}{\bar{\partial}}    
        & \s{A}^{1,0}\arrow{r}{\partial}\arrow{d}{\bar{\partial}}    
        & \dots\arrow{r}{\partial}\arrow{d}{\bar{\partial}}    
        & \s{A}^{n,0}\arrow{r}\arrow{d}{\bar{\partial}} 
    & 0 \\
    & 0 \arrow{r} 
        & \s{A}^{0,1} \arrow{r}{\partial}\arrow{d}{\bar{\partial}} 
        & \s{A}^{1,1}\arrow{r}{\partial}\arrow{d}{\bar{\partial}}
        & \dots \arrow{r}{\partial}\arrow{d}{\bar{\partial}}
        & \s{A}^{n,1}\arrow{r}\arrow{d}{\bar{\partial}}
    & 0 \\
    &
        & \tvdots\arrow{r}{\partial}\arrow{d}{\bar{\partial}}
        & \tvdots\arrow{r}{\partial}\arrow{d}{\bar{\partial}}
        & \tvdots\arrow{r}{\partial}\arrow{d}{\bar{\partial}}
        & \tvdots\arrow{r}{\partial}\arrow{d}{\bar{\partial}}
    & \\
    & 0 \arrow{r}
        & \s{A}^{0,n}\arrow{r}{\partial}
        & \s{A}^{1,n}\arrow{r}{\partial}
        & \dots\arrow{r}{\partial}
        & \s{A}^{n,n}\arrow{r}{\partial}
    & 0\\
    \end{tikzcd}
\end{document}

Since I need to draw the same diagram multiple times, I thought that I could define a control sequence

\def\DoubleComplex{
"All the code you saw above"
}

When I try to compile it using

\[
     \DoubleComplex
\]

I keep getting the following error message:

! Missing $ inserted.
<inserted text> 
            $
l.234     \DoubleComplex

I wonder what is going on? And what would be a good way to reuse a commutative diagram?

Answer 1

Tikz makes & an active character, which may lead to problems in certain contexts. Add [ampersand replacement=\&] to the tikzcd environment and use \& in the diagram instead of &.

I found another problem with your code: In the fourth row the seventh cell is empty, which results in a tikcd error (No shape named tikz@f@1-4-7 is known) because the destination for the arrow from the sixth cell is missing. It seems to be sufficient to add {} as contents of the empty cell.

\documentclass{article}
\usepackage{tikz-cd}
\newcommand\s[1]{\mathsf{#1}}
\makeatletter
\DeclareRobustCommand{\tvdots}{%
  \vbox{\baselineskip4\p@\lineskiplimit\z@\kern0\p@\hbox{.}\hbox{.}\hbox{.}}}
\makeatother
\newcommand\DoubleComplex
  {\begin{tikzcd}[ampersand replacement=\&]
    \& 0 \arrow{r} 
        \& O_X \arrow{r}{\partial}\arrow{d}{i} 
        \& \Omega^1_X \arrow{r}{\partial}\arrow{d}{i} 
        \& \dots\arrow{r}{\partial}\arrow{d}{i} 
        \& \Omega^n_X\arrow{r}\arrow{d}{i} 
    \& 0 \\
    \& 0 \arrow{r} 
        \& \s{A}\arrow{r}{\partial}\arrow{d}{\bar{\partial}}    
        \& \s{A}^{1,0}\arrow{r}{\partial}\arrow{d}{\bar{\partial}}    
        \& \dots\arrow{r}{\partial}\arrow{d}{\bar{\partial}}    
        \& \s{A}^{n,0}\arrow{r}\arrow{d}{\bar{\partial}} 
    \& 0 \\
    \& 0 \arrow{r} 
        \& \s{A}^{0,1} \arrow{r}{\partial}\arrow{d}{\bar{\partial}} 
        \& \s{A}^{1,1}\arrow{r}{\partial}\arrow{d}{\bar{\partial}}
        \& \dots \arrow{r}{\partial}\arrow{d}{\bar{\partial}}
        \& \s{A}^{n,1}\arrow{r}\arrow{d}{\bar{\partial}}
    \& 0 \\
    \&
        \& \tvdots\arrow{r}{\partial}\arrow{d}{\bar{\partial}}
        \& \tvdots\arrow{r}{\partial}\arrow{d}{\bar{\partial}}
        \& \tvdots\arrow{r}{\partial}\arrow{d}{\bar{\partial}}
        \& \tvdots\arrow{r}{\partial}\arrow{d}{\bar{\partial}}
    \& {}\\
    \& 0 \arrow{r}
        \& \s{A}^{0,n}\arrow{r}{\partial}
        \& \s{A}^{1,n}\arrow{r}{\partial}
        \& \dots\arrow{r}{\partial}
        \& \s{A}^{n,n}\arrow{r}{\partial}
    \& 0\\
    \end{tikzcd}%
  }
\begin{document}
First occurrence:
\[ \DoubleComplex \]
Second occurrence:
\[ \DoubleComplex \]
\end{document}