# Arrow with two tails and a latex arrow tip

How to draw an arrow with two tails in tikzcd (or tikz) with a latex arrow tip? If I use \ar[Rightarrow], I get the default arrow tip. If I use \ar[double], I can get a latex arrow tip, but the two tails are too close to each other.

Here is a minimal example:

\documentclass[12pt]{article}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage[english]{babel}
\usepackage{amsmath}
\usepackage{tikz-cd}
\tikzset{commutative diagrams/.cd, arrow style=tikz, diagrams={>=latex}}

\begin{document}

$\begin{tikzcd} A \ar{rr} \ar{dr} & \ar[Rightarrow]{d} & B \\ & C \ar{ur} & \end{tikzcd}$

$\begin{tikzcd} A \ar{rr} \ar{dr} & \ar[double]{d} & B \\ & C \ar{ur} & \end{tikzcd}$

\end{document}

• Maybe double distance. – Symbol 1 Jun 8 '17 at 12:44
• Oh yes, double distance = 0.3ex works. I will accept this as an answer, if you post it as such. – HeinrichD Jun 8 '17 at 12:45

While Rightarrow is a option, double is a TikZ option and is usually used together with double distance/double distance between line centers/double equal sign distance.
It is worth noting that double equal sign distance will setup the double distance such that a doubled line is compatible with the equal sign (assuming the standard font.)
Following this remark, one may find that uses double equal sign distance to define double line. And then it uses double line to define Rightarrow/Leftarrow/Leftrightarrow/Mapsto/Mapsfrom/equal/equals.