How to set the size of a single symbol defined via \DeclareMathSymbol?

Question

I am using the following definition for a symbol I call \nstn:

\DeclareSymbolFont{largesym}{OML}{cmm}{m}{it}
\DeclareMathSymbol{\nstn}{0}{largesym}{"22}

How can I set the size of this single symbol (which is basically \varepsilon) to a specific number (I would like it to be larger than usual/default)?

Answer 1

You could just declare one symbol, and then define another using a scalebox or something...

\documentclass{article}
\usepackage{graphicx}
\DeclareSymbolFont{largesym}{OML}{cmm}{m}{it}
\DeclareMathSymbol{\nstnsmall}{0}{largesym}{"22}
\newcommand{\nstn}{\mathrel{\scalebox{1.5}{$\nstnsmall$}}}

\begin{document}
\[
A \nstn B
\]
\end{document}

You might change \mathrel to \mathord or \mathop or something depending on the mathematical syntax category. For some reason this said "relation sign" to me.

Answer 2

You can by-pass NFSS and use TeX primitives:

\documentclass{article}
\DeclareFixedFont{\nstnfont}{OML}{cmm}{m}{it}{14.5pt}
\newfam\nstnfam
\textfont\nstnfam=\nstnfont
\makeatletter
\set@mathsymbol\nstnfam\nstn\mathbin{22}
\makeatother
\begin{document}
\[ A \nstn B \]
\end{document}