Replacing a single letter from another font in mathspec

Question

I want to replace the letter "f" from a certain font family with "f" from another font family. My current attempt at doing so is the following.

\documentclass{minimal}
\usepackage{graphicx}
\usepackage{physics} 
\usepackage{mathspec}
\defaultfontfeatures{Mapping=tex-text,}
\setmathsfont(Digits){Old Standard}
\setmathsfont(Latin)[Uppercase=Italic,Lowercase=Italic]{Old Standard}
\makeatletter
\DeclareSymbolFont{alphabets}{\encodingdefault}{pmn}{m}{it}
\SetSymbolFont{alphabets}{normal}{\encodingdefault}{pmn}{m}{it}
\SetSymbolFont{alphabets}{bold}{\encodingdefault}{pmn}{b}{it}
\DeclareMathSymbol{f}{\mathalpha}{alphabets}{"66}
\makeatother
\begin{document}
    Print $f$.
\begin{align*}
    F(x)
         &amp; = \sum_{d\mid n}f(d)
\end{align*}\\[1cm]

\end{document}

However, it does not produce the math/italic version of "f", only a straight text version. How can I make this italic?

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score 3 · Accepted Answer · answered Oct 01 '21 at 23:32

I assume you want Minion Pro. For this to succeed you need to declare a font family and assign it a NFSS name.

\documentclass{article}
\usepackage{amsmath}
%\usepackage{graphicx}
%\usepackage{physics}
\usepackage{mathspec}
\defaultfontfeatures{Mapping=tex-text,}
\setmathsfont(Digits){Old Standard}
\setmathsfont(Latin)[Uppercase=Italic,Lowercase=Italic]{Old Standard}
\newfontfamily{\minion}{Minion Pro}[NFSSFamily=pmn]
\DeclareSymbolFont{alphabets}{\encodingdefault}{pmn}{m}{it}
\SetSymbolFont{alphabets}{bold}{T1}{pmn}{b}{it}
\DeclareMathSymbol{f}{\mathalpha}{alphabets}{"66}
\begin{document}
Print $f$.
\begin{equation}
  F(x) = \sum_{d\mid n}"f(d)
\end{equation}
\end{document}

Without this approach you got warnings about not existing fonts that are substitute with others.

Replacing a single letter from another font in mathspec

1 Answers1