1

I use this code in beamer:

\[
\begin{tikzpicture}[>=angle 90]
\matrix(a)[matrix of math nodes,
row sep=2.5em, column sep=2.5em,
text height=1.5ex, text depth=0.20ex, ampersand replacement=\&]
{\bigwedge^2 S^m\&S^m\&S\&0\\
F_2\&F_1\&S\&0\\};
\draw[->](a-1-1) -- (a-1-2);
\draw[->](a-1-2) -- (a-1-3);
\draw[->](a-1-3) -- (a-1-4);
\draw[->](a-2-1) -- (a-2-2);
\draw[->](a-2-2) -- (a-2-3);
\draw[->](a-2-3) -- (a-2-4);
\draw[->](a-1-1) -- node[auto] {$\gamma$}(a-2-1);
\draw[->](a-1-2) -- node[auto] {$\cong$}(a-2-2);
\draw[double equal sign distance,shorten <=5pt,shorten >=5pt](a-1-3) -- node[auto]   {$id$}(a-2-3);
\end{tikzpicture}
\]

but I don't get the double line between (a-1-3) and (a-2-3), why?

(I took this code here: How can I do this diagram with tikz?)

David Carlisle
  • 757,742
Peter E
  • 717

2 Answers2

1

Try replacing double equal sign distance with double,double distance=3pt. (Still not exactly this, but closer.)

A quick and dirty workaround is:

\draw[shorten <=5pt,shorten >=5pt,line width=3.8pt](a-1-3) -- node[auto]   {$id$}(a-2-3);
\draw[shorten <=4pt,shorten >=4pt,line width=3pt,color=white](a-1-3) -- node[auto]   {$id$}(a-2-3);

(This does a similar thing as double, but manually and prevents "sticking out" of the middle (white) part of the line.)

mbork
  • 13,385
0

Your code worked for me and I noticed a double line, as expected. It may be viewer issue.

  • Try zooming in to see if the single line changes to a double line at a higher zoom level

  • Try a different PDF viewer

  • Print it onto paper to verify

If it's just a viewer issue you don't need to change your code. You could get around by raising distance or line thickness regarding visibilty and greyness though.

Stefan Kottwitz
  • 231,401