Extensible double lined, squiggle arrow

Question

I would need an arrow (for math mode) with the following characteristics:

• squiggle (like \rightsquigarrow)
• double lined (like \xRightarrow)
• extendible (like \xRightarrow)

Currently, I am using macros like this...

\newcommand{\myDoubleArrow}{\ensuremath{\smash{\xRightarrow[{\scriptscriptstyle \donotsmash{#2} \mkern+4mu}]{ \vbox{\hbox{\ensuremath{\scriptscriptstyle \donotsmash{#1} \mkern+4mu}}\vskip -1.0pt} }}}}

Do you know any neat possibility to get such an arrow? It should be usable as the command above (however, I only need text on top of the arrow)

Thanks in advance!

Answer 1

One possibility using a variation of the answer to How to create a squiggle arrow with some text on it in TikZ?:

\documentclass{article}
\usepackage{amsmath,amssymb}
\usepackage{mathtools}
\usepackage{tikz}
\usetikzlibrary{calc,decorations.pathmorphing,shapes,arrows}

\newcommand\xrsquigarrow[1]{%
\mathrel{%
\begin{tikzpicture}[baseline= {( $ (current bounding box.south) + (0,-0.5ex) $ )}]
  \node[inner sep=.5ex] (a) {$\scriptstyle #1$};
  \path[draw,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}

\[ 
A\xRightarrow{f} B\quad A\rightsquigarrow B\quad A\xrsquigarrow{f}B\quad A\xrsquigarrow{(f\circ g)\circ h}B
\]

\end{document}