How to insert a special math alphabet

Question

I am trying to insert a special math alphabet in an equation for a physics quantity called "cavity finesse". It is basically represented by a fancy letter F, which looks like what's shown in the picture. (ref: http://mirrors.ctan.org/macros/latex/contrib/mathalpha/doc/mathalpha-doc.pdf).

After doing some research, it seems that I need to download a math package in order to use it, but most of which is not free. All I need is this only one letter from the package, and will probably use it for a couple of times only. Is there any easy way to insert it?

I am using \mathcal{F} right now (shown in the bottom picture), but it does not look as great.

Answer 1

With a default TeX installation, for example, you could produce any of these (among other options):

with code something like this:

\documentclass{article}
\usepackage[T1]{fontenc}
\DeclareFontFamily{T1}{calligra}{}
\DeclareFontShape{T1}{calligra}{m}{n}{<->s*[1.44]callig15}{}
\DeclareMathAlphabet\mathcalligra   {T1}{calligra} {m} {n}
\DeclareMathAlphabet\mathzapf       {T1}{pzc} {mb} {it}
\DeclareMathAlphabet\mathchorus     {T1}{qzc} {m} {n}
\DeclareMathAlphabet\mathrsfso      {U}{rsfso}{m}{n}
\begin{document}
\Huge
\noindent
      $\mathzapf{F}$\marginpar{Zapf}\\
      $\mathchorus{F}$\marginpar{tgchorus}\\
      $\mathcalligra{F}$\marginpar{calligra}\\
      $\mathrsfso{F}$\marginpar{rsfso}\\
\end{document}

Answer 2

The dutchcal package makes the dutchcal fonts ready-to-use. They're derived from the esstix fonts, which are a times-like font, slightly reworked. If you're under MiKTeX, after installing them with MiKTeX Package Manager, as often you'll need to launch updmap in order to make the fonts completely available.

    \documentclass{article}
    \usepackage{dutchcal}

    \begin{document}
     $ \mathcal{F}\enspace  \mathbcal{F}$

    \end{document} 

There is also a bickham package, but having the fonts really available to your TeX system is more involved, as Bickham is an opentype font, it has to be converted to type 1 with the LCDF Type Tools.

Answer 3

You might also try the version that is available by using \mathcal{F} with \usepackage{F}. This give what is (in my opinion) a much more pleasing calligraphic script:

Code:

\documentclass[]{article}
\usepackage{eucal}
\begin{document}

% eucal redefines \mathcal command but keeps original
% Computer Modern version available as \CMcal
$\CMcal{F}$ Original \verb!\mathcal{F}!

$\mathcal{F}$ \verb!\mathcal{F}! with \verb!eucal! 


\end{document}

For more info, see Are there two different versions of the \mathcal{F} character?.

Answer 4

In a sample of Unicode system fonts (accessed via package unicode-math), degrees of curliness are available for the symbol shape:

MWE:

\documentclass[12pt]{article}
\usepackage{xcolor}
\pagecolor{red!3}
\usepackage{unicode-math}
\setmathfont{XITS Math}[Colour=blue]
\setmathfontface\masana{Asana Math}
\setmathfontface\mdejavu{DejaVu Math}
\setmathfontface\mtgdeja{TeX Gyre DejaVu Math}
\setmathfontface\mpagella{TeX Gyre Pagella Math}
\setmathfontface\mbonum{TeX Gyre Bonum Math}
\setmathfontface\mschola{TeX Gyre Schola Math}
\setmathfontface\mtermes{TeX Gyre Termes Math}
\setmathfontface\mlatin{Latin Modern Math}
\setmathfontface\mcambria{Cambria Math}
\setmathfontface\mfira{Fira Math}
\setmathfontface\mfreeserif{FreeSerif}
\setmathfontface\mlibert{Libertinus Math}
\setmathfontface\mnoto{Noto Sans Symbols}
\setmathfontface\mqui{Quivira}
\setmathfontface\mstixtwo{STIX Two Math}
\setmathfontface\mstixgen{STIXGeneral}
\setmathfontface\msymbola{Symbola}
\setmathfontface\mgaramond{\detokenize{Garamond-Math}}
\newcommand\mfsize{\Huge}
\setmainfont{Noto Serif}


%mas = Mathematical Alphanumeric Symbols block in unicode
\newcommand\themassym{ℱ}
\begin{document}
\section {Sampling {\mfsize $\symcal{F}$}}%symbol name comes from   unicode-math-table.tex

This is script {\mfsize $\symcal{F}$} (unicode Letterlike Symbols U+2131) in math mode: 


\vspace{24pt}

\begin{tabular}{rccl}
XITS Math & \mfsize $\themassym$ & \mfsize $\mcambria \themassym$ & Cambria Math \\ 
\ &\ & \ & \ \\ 
Asana Math & \mfsize $\masana {\themassym}$ & \mfsize $\mfira \themassym$ & Fira Math (no script series)\\ 
\ &\ & \ & \ \\ 
DejaVu Math & \mfsize $\mdejavu \themassym$ & \mfsize $\mfreeserif \themassym$ & FreeSerif \\
\ &\ & \ & \ \\ 
Tex Gyre Bonum Math & \mfsize $\mbonum \themassym$ & \mfsize $\mlibert \themassym$ & Libertinus Math \\
\ &\ & \ & \ \\ 
Tex Gyre DejaVu Math & \mfsize $\mtgdeja \themassym$ & \mfsize $\mnoto \themassym$ & Noto Sans Symbols \\
\ &\ & \ & \ \\ 
Tex Gyre Pagella Math & \mfsize $\mpagella \themassym$ & \mfsize $\mqui \themassym$ & Quivira \\
\ &\ & \ & \ \\ 
Tex Gyre Schola Math & \mfsize $\mschola \themassym$ & \mfsize $\mstixtwo \themassym$ &STIX Two Math \\
\ &\ & \ & \ \\ 
Tex Gyre Termes Math & \mfsize $\mtermes \themassym$ & \mfsize $\mgaramond \themassym$ & Garamond-Math \\
\ &\ & \ & \ \\ 
Latin Modern Math & \mfsize $\mlatin \themassym$ & \mfsize $\msymbola \themassym$ & Symbola \\
\end{tabular}

\end{document}