symbols
Is there a way to create a box with a check mark in the center of it and the check mark coming out of the box?
For example: $\boxdot$ or $\boxtimes$, but instead have a check mark placed at the center extending outside the box.
P.S. How can I get things to work in math mode on this site. For example, the above sample code does not display the pictures.
Here's a solution that doesn't require the use of additional packages. The new command, \vertiii, takes one argument; the triple vertical bars resize automatically depending on the size of the argument. For the MWE below, I've actually set the spacing between the vertical bars to be slightly less than what's generated by \[l,r]Vert -- you can adjust the spacing to suit your taste by changing the value of the argument of the four \kern commands.
Addendum: I've modified the code -- by inserting curly braces around the entire command -- to allow for the use of the command \vertiii in subscripts and superscripts as well.
\documentclass{article}
\usepackage{amsmath,amssymb}
\newcommand{\vertiii}[1]{{\left\vert\kern-0.25ex\left\vert\kern-0.25ex\left\vert #1
\right\vert\kern-0.25ex\right\vert\kern-0.25ex\right\vert}}
\begin{document}
$\vertiii{a}$,
$\vertiii{\int_0^1 a(x)\,\mathrm{d}x}$,
$\displaystyle \vertiii{\int_0^1 a(x)\,\mathrm{d}x}_\vertiii{b}$
$\lVert a \rVert$ (for comparison)
$c_\vertiii{d}$, $f^\vertiii{g}$
\end{document}
Why not use the already available \boxtimes?
\documentclass{article}
\usepackage{amssymb}
\begin{document}
$\boxtimes$
\end{document}
Best Answer
One can choose between the following two solutions; the first one centers the two symbols with respect to one another, the second one draws the square and then displaces the check mark.
By acting on the two dimensions, one can find by trial and error the best relative positioning of the check mark with respect to the box.
This gives (with magnification x16 and displayed horizontally):