How to create an Arrow Symbol

Question

I am looking for a way to create a symbol of an arrow in which it points in a downward direction but do not know if one already exist. I have tried detexify to come up with nothing.

The picture of the arrow is below:

Answer 1

Using TikZ you can define a command that will give you a stretchable symbol; you can do something like this:

\documentclass{book}
\usepackage{tikz}

\newcommand\myarrow[1][1]{%
  \raisebox{-0.5cm}{\begin{tikzpicture}\draw (0,0) -- (#1,0); \draw[->] (#1,0) -- (#1,-0.5);\end{tikzpicture}}}

\begin{document}
\noindent\myarrow[6.4]
\begin{equation}
  x^n + y^n = z^n.
\end{equation}

\noindent\myarrow[4.8]
\begin{equation}
  a= b + c + d + e + f.
\end{equation}

\end{document}

Answer 2

This might be what you are looking for:

\usepackage{graphicx,amssymb}

\newcommand{\rRsh}{\rotatebox[origin=c]{-90}{$\Rsh$}}

Try $X\rRsh Y$ and make your comments.

If mathabx is loaded instead of amssymb, the same definition produces a symbol with two equal segments.

To get an extensible horizontal bar, define

\newcommand{\longrRsh}[1]{%
  \makebox[#1]{\leaders\hrule height 1.25ex depth -1.16ex\relax
    \hfil\kern-1pt\rRsh}}

and then \longrRsh{3cm} will produce a 3cm long symbol (the figures are optimized for the amssymb version).

Answer 3

This is not quite what you are looking for but might be good enough:

\documentclass{article}
\usepackage{amsmath}
\usepackage{MnSymbol}
\begin{document}
\[
    a \rhookdownarrow b
\]
\end{document}