# Alternate to ugly \parallel and \sslash symbols in subscript mathmode

I'm looking for a nicer "parallel" symbol that matches the \perp symbol, when used in subscripts. Here's a MWE showing the \parallel, \perp, \sslash and two custom symbols (currently called \para and \paral):

\documentclass[11pt,letterpaper,twoside]{book}
\usepackage[T1]{fontenc}
\usepackage{lmodern}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{mathtools}
\usepackage{mathrsfs}
\usepackage{upgreek}
\usepackage{stmaryrd}

\newcommand*{\paral}{\scalebox{0.6}{$\slash\!\slash$}}

\newcommand*{\para}{\rotatebox[origin=c]{45}{$\scalebox{0.8}{=}$}}

\begin{document}

Blabla:
$$v_{\parallel \perp}v_{\sslash \perp}v_{\paral \perp}v_{\para \perp}.$$

\end{document}


Preview:

As any cat could see here, the first one (\parallel) is too high compared to the \perp symbol next to it. I hate it and prefer to leave it to the dogs! It causes ugly spacements problems especially in fractions. The second one (\sslash in the second term) is not much better. The third one (custom \paral) is a bit better but there's a vertical offset that annoys the cat in me. The fourth one (\para) is much closer to the one I'm looking, which fits better to the \perp next to it (its size could be adjusted a bit, and there's also a vertical offset though).

So I'm wondering if there's a better solution that I'm unaware of. What would you suggest to get the best looking parallel symbol in subscript position that would complement the nice \perp symbol in shape, size and readability? How would you modify the macros I've defined in the code above?

Thank you very much and get a nice cat meal for free!

You could use \stretchrel from the scalerel package.

\documentclass[11pt,letterpaper,twoside]{book}
\usepackage[T1]{fontenc}
\usepackage{lmodern}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{mathtools}
\usepackage{mathrsfs}
\usepackage{upgreek}
\usepackage{stmaryrd}

\usepackage{scalerel}

\newcommand*{\paral}{\stretchrel*{\parallel}{\perp}}
\newcommand*{\Sslash}{\stretchrel*{\sslash}{\perp}}

\begin{document}

Blabla:
$$v_{\parallel \perp}\quad\text{vs.}\quad v_{\paral \perp} \quad\text{and}\quad v_{\sslash \perp}\quad\text{vs.}\quad v_{\Sslash \perp}\;.$$

\end{document}


• Very nice. May be the best solution... – Cham Jan 11 at 18:22
• Very very nice!! Just wow! Which one is better? \Sslash or \paral? – Cham Jan 11 at 18:25
• @Cham Purrrrrrr – Schrödinger's cat Jan 11 at 18:26
• You'll get two free cat meals for this, ... and a mouse to play with... – Cham Jan 11 at 18:27