Importing two symbols from stix2

Question

I want to import two math symbols from stix2 package: \rdiagovfdiag and \fdiagovrdiag which look like this:

I want to do this, because adding the whole package changes style of my article which I don't like. I've seen in different posts (e.g. here) that it is possible, but I don't know how to modify these examples in my situation.

Answer 1

The idea is to make a copy of stix2.sty, search for the lines that define the two symbols, delete everything after these lines, and then going backwards to retain only those lines that are needed for defining the symbols.

Save the following lines in a file mystix2.sty.

\NeedsTeXFormat{LaTeX2e}[1999/12/01]
\ProvidesPackage{mystix2}[2023/11/10 pick X symbols from stix2.sty]
\DeclareFontEncoding{LS1}{}{}
\DeclareFontSubstitution{LS1}{stix2}{m}{n}
\DeclareSymbolFont{arrows2}       {LS1}{stix2sf}   {m}{it}
\SetSymbolFont{arrows2}     {bold}{LS1}{stix2sf}   {b}{it}
\def\stix@undefine#1{%
    \if\relax\noexpand#1\let#1=\@undefined\fi}
\def\stix@MathSymbol#1#2#3#4{%
    \stix@undefine#1%
    \DeclareMathSymbol{#1}{#2}{#3}{#4}}
\stix@MathSymbol{\rdiagovfdiag}{\mathord}{arrows2}{"C4}
\stix@MathSymbol{\fdiagovrdiag}{\mathord}{arrows2}{"C5}
\endinput

Use it like in the following sample document.

\documentclass{article}
\usepackage{mystix2}
\begin{document}
$\rdiagovfdiag$ $\fdiagovrdiag$
\end{document}

Answer 2

You need no package, actually.

The idea is to look how the commands are defined in stix2.sty and you find

\stix@MathSymbol{\rdiagovfdiag}{\mathord}{arrows2}{"C4}
\stix@MathSymbol{\fdiagovrdiag}{\mathord}{arrows2}{"C5}

OK, now we want to see what arrow2 points to:

\DeclareSymbolFont{arrows2}       {LS1}{stix2sf}   {m}{it}
\SetSymbolFont{arrows2}     {bold}{LS1}{stix2sf}   {b}{it}

We have to look for LS1, which is a nonstandard encoding:

\DeclareFontEncoding{LS1}{}{}
\DeclareFontSubstitution{LS1}{stix2}{m}{n}

OK, we have all the ingredients. I add a prefix just to be sure that nothing gets clobbered.

\documentclass{article}
\usepackage{amsmath}

\DeclareFontEncoding{LS1}{}{}
\DeclareFontSubstitution{LS1}{stix2}{m}{n}
\DeclareSymbolFont{STIX2arrows2}{LS1}{stix2sf}{m}{it}
\SetSymbolFont{STIX2arrows2}{bold}{LS1}{stix2sf}{b}{it}

\DeclareMathSymbol{\rdiagovfdiag}{\mathord}{STIX2arrows2}{"C4}
\DeclareMathSymbol{\fdiagovrdiag}{\mathord}{STIX2arrows2}{"C5}

\begin{document}

$A\rdiagovfdiag\fdiagovrdiag B$

\end{document}

If you don't need the bold version, you can even avoid wasting a math group:

\documentclass{article}
\usepackage{amsmath}

\DeclareFontEncoding{LS1}{}{}
\DeclareFontSubstitution{LS1}{stix2}{m}{n}

\NewDocumentCommand{\rdiagovfdiag}{}{\text{\usefont{LS1}{stix2sf}{m}{it}\symbol{"C4}}}
\NewDocumentCommand{\fdiagovrdiag}{}{\text{\usefont{LS1}{stix2sf}{m}{it}\symbol{"C5}}}

\begin{document}

$A\rdiagovfdiag\fdiagovrdiag B$

\end{document}