I am trying to create a double-lined arrow pointing to both sides like \Leftrightarrow
with a squiggly line. The Comprehensive LaTeX Symbol List did not seem to contain any such symbol, nor did other (seemingly less comprehensive) lists of LaTeX symbols.
I thought I could adapt the solution from this answer to a similar question (about a double-lined squiggly arrow pointing into one direction. I tried using the information provided in this answer on how to obtain an arrow pointing to both directions.
As I did not want any text above the arrow, in my first attempt I made the text invisible and just used it to give the arrow its length:
\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{calc,decorations.pathmorphing,shapes,arrows}
\newcommand\xlrsquigarrow{%
\mathrel{%
\begin{tikzpicture}[baseline= {( $ (current bounding box.south) + (0,-0.5ex) $ )}]
\node[inner sep=.5ex] (a) {\textcolor{white}{m}};
\path[draw,implies-implies,double distance between line centers=1.5pt,decorate,
decoration={zigzag,amplitude=0.7pt,segment length=1.2mm,pre=lineto,
pre length=4pt}]
(a.south east) -- (a.south west);
\end{tikzpicture}}%
}
\begin{document}
a $\xlrsquigarrow$ b
\end{document}
Unfortunately, this looks like this:
For some reason, the left arrowhead is rotated by 90° and pointing upward.
Therefore, I decided to remove the obsolte remainder of the original solution (i.e. the node with the text I didn't need) and use absolute coordinates:
\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{calc,decorations.pathmorphing,shapes,arrows}
\newcommand\xlrsquigarrow{%
\mathrel{%
\begin{tikzpicture}[baseline= {( $ (current bounding box.south) + (0,-0.5ex) $ )}]
\path[draw,implies-implies,double distance between line centers=1.5pt,decorate,
decoration={zigzag,amplitude=0.7pt,segment length=1.2mm,pre=lineto,
pre length=4pt}]
(0,0) -- (0.5,0);
\end{tikzpicture}}%
}
\begin{document}
a $\xlrsquigarrow$ b
\end{document}
I would have expected that at worst, nothing would be changed (I've just exchanged two coordinates, right?), and at best, that it works now. However:
Now, the right arrowhead is rotated by 90° and pointing upward!
Why are those arrowheads rotated and how do I achieve the desired result?
(Non-Tikz solutions, if any, are welcome, too - I just chose Tikz because I couldn't find a ready-made symbol and this seemed like the most straightforward way. That notwithstanding, I would like to understand why the attempted Tikz solutions shown above behave the way they do.)