Better way to produce V\llap{--}

Question

Is there a better way to get the symbol produced by V\llap{--}? I need it in math mode. The symbol is someitmes used to represent volume. The above hack is not the right symbol but something close.

Answer 1

\documentclass{article}
\newcommand{\volume}{{\ooalign{\hfil$V$\hfil\cr\kern0.08em--\hfil\cr}}}
\begin{document}
$\volume(abc)$
\end{document}

A better implementation, where the dash is built as above, but over a phantom V; the real one is added later, so subscripts and superscripts are placed with respect to it.

\documentclass{article}
\usepackage{amsmath}

\makeatletter
\DeclareRobustCommand{\volume}{\text{\volumedash}V}
\newcommand{\volumedash}{%
  \makebox[0pt][l]{%
    \ooalign{\hfil\hphantom{$\m@th V$}\hfil\cr\kern0.08em--\hfil\cr}%
  }%
}
\makeatother

\begin{document}

$d\volume(abc)$

$x^{}_{\volume}$

$\volume_x$

$V_x$

\end{document}

Answer 2

I was looking for the same thing, but found it a bit distracting to have the cross extend beyond the lines of the V. I came up with an alternative approach:

\documentclass{article}

\usepackage{graphicx}

\newcommand{\Vol}{\rotatebox[origin=c]{180}{\ensuremath{A}}}

\begin{document}
    Let $\Vol$ represent system volume.
\end{document}

Answer 3

Here you go. Inspired by @egreg's answer. You can adjust the position parameters in the code.

\ooalign{$V$\cr\raisebox{0.15em}{\kern0.04em--}\cr}

Answer 4

Another simple alternative using \makebox command with the same name of @egreg's named \volume:

\documentclass[a4paper,12pt]{article}
\newcommand{\volume}{\makebox[1pt][l]{$-$}V}
\begin{document}
\[\frac{d\volume(x,y,z)}{dz}\]
\end{document}