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I know versions of this question have already been asked, but I've already spent a couple of hours trying to make their answers work in my case, and wasn't able to.

I would like a dedicated symbol to use for Kronecker deltas, which doesn't get confused with other deltas in my document. For this I would like to import the delta from one of the fonts in this list, say the one on page 9. I only want to import one character, and would like a new command for it that does not overwrite the ordinary \delta. What is the quickest way to achieve this?

Thank you.

Emilio Ferrucci
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  • Antykwa Toruńska font (you can see to pag. 30, https://ctan.mirror.garr.it/mirrors/CTAN/fonts/antt/doc/fonts/antt/AntykwaTorunska-doc-en-2_03.pdf - https://www.ctan.org/tex-archive/fonts/psfonts/anttvf) have the symbol \delta the nr. 228: \symbol{228}. – Sebastiano Jul 25 '20 at 15:15
  • Thanks for the comment. I still don't see how to load that character individually (if I \usepackage{anttor} the font for the whole document changes). – Emilio Ferrucci Jul 25 '20 at 15:19
  • Are you sure your readers will notice the difference? – egreg Jul 25 '20 at 20:25
  • @egreg probably not, but I might draw their attention to it. There are other (non-Kronecker) deltas in the same equations, so I think it's nice to have a different symbol. – Emilio Ferrucci Jul 25 '20 at 23:07

1 Answers1

2

The solution will be different depending on whether you use unicode-math or legacy 7-bit math fonts. Here is a solution that uses unicode-math if the engine supports it, and otherwise falls back to the font you specified:

\documentclass{article}
\usepackage{iftex} % For /iftutex
\usepackage[paperwidth=10cm]{geometry} % To format this MWE for TeX.SX
\pagestyle{empty}

\iftutex
  % LuaTeX or XeTeX
  \usepackage{unicode-math}
  \setmathfontface\altgrfont{AntykwaTorunskaMed-Italic.otf}[Scale=MatchLowercase]
  \newcommand{\kronecker}{\altgrfont{δ}}
\else
  % PDFTeX
  \usepackage[T1]{fontenc}
  \usepackage[utf8]{inputenc} % The default since 2018
  \usepackage{amsmath}
  \DeclareSymbolFont{altgr}{OML}{antt}{m}{it}
  \DeclareMathSymbol{\kronecker}{\mathord}{altgr}{"0E}
\fi


\begin{document}
\begin{tabular}{c c c}
  Kronecker delta & \texttt{{\textbackslash}delta} & \texttt{{\textbackslash}partial} \
  (\kronecker)  & (\delta)                 & (\partial)
\end{tabular}
\end{document}

antt font sample

In PDFTeX, you can change the family name to get another font, or even change OML to LGR to use a LGR-encoded font. if you don’t want to waste one of your limited number of math alphabets on this one symbol, you could instead switch to \textnormal and generate it with text-mode commands, e.g. \usefont followed by \symbol.

You would need one extra line of code in each case to declare a bold version, which you might for example use in a bold header.

Davislor
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