Double slashes close together with resizing

Question

I basically want this symbol, but I want it to resize properly: While

X/\mkern-6mu/H

looks good, when I try to resize using \biggl, then the horizontal space between the two slashes becomes very large:

\biggl.X\biggl/\mkern-6mu\biggl/H\biggr.

Is there any solution to this? None of the suggestions in the original question resize properly.

Thanks a lot in advance!

Answer 1

First of all, \biggl. and \biggr. do exactly nothing, except introduce unwanted opening and closing atoms (and, possibly, the relative spacing).

Second, \bigl/ makes the bigger / an opening atom, so you should use \big, instead.

Third, the bigger / has wider sidebearings than the normal size symbol. If you need it only at normal and \big size, here's a way:

\documentclass{article}
\usepackage{xparse}

\NewDocumentCommand{\dslash}{s}{%
  \IfBooleanTF{#1}
    {\big/\mkern-7mu\big/}
    {/\mkern-6mu/}%
}

\begin{document}
$X\dslash H$

$X\dslash* H$
\end{document}

If you want other sizes, then something more complex should be devised. Here's an example:

\documentclass{article}
\usepackage{xparse}

\ExplSyntaxOn
\NewDocumentCommand{\dslash}{O{}}
 {
  \str_case:nn { #1 }
   {
    {}{/\mkern-6mu/}
    {\big}{\big/\mkern-7mu\big/}
    {\Big}{\Big/\mkern-10mu\Big/}
    {\bigg}{\bigg/\mkern-14mu\bigg/}
    {\Bigg}{\Bigg/\mkern-18mu\Bigg/}
   }
 }
\ExplSyntaxOff

\begin{document}
$X\dslash H$

$X\dslash[\big] H$

$X\dslash[\Big] H$

$X\dslash[\bigg] H$

$X\dslash[\Bigg] H$
\end{document}