French math style with default font

Question

Edit: Okay, I found it, just needed more focus on the related entry. The package mathastext called with the frenchmath option does the job.

The time for my first question to stackexchange could have been delayed...

Original question:

I've realized that French typography uses a different style for mathematics, namely upright uppercase roman letters and lowercase greek letters (roman lowercase remaining in italic), while default LaTeX is italic. What I want is to use this style with the default math font.

I found far less resources on the Web than I expected, like this one, which introduces math font packages with options for French (or ISO) math style. Nevertheless I'm quite unhappy with the general look of these fonts, not mentioning the fact that unicode-math seems to clash with amssymb.

This related question has been answered with:

Simply put these in your preamble:

\everymath\expandafter{\the\everymath\mathgroup0}
\everydisplay\expandafter{\the\everydisplay\mathgroup0}

It doesn't look good though, so I guess you may also want to change font.

which I guess is interesting for my issue, but not explained a single bit and I don't know how, or if, I can adapt it.

Answer 1

You wrote,

not mentioning the fact that unicode-math seems to clash with amssymb

What's the basis for this claim? The packages get along fine as long as amssymb is loaded first.

If you can use either XeLaTeX or LuaLaTeX to compile your document, specifying the option math-style=french while running \setmathfont lets you achieve all of your locale-related formatting objectives.

% !TEX TS-program = lualatex
\documentclass{article}
\usepackage{amsmath,amssymb,booktabs}
\usepackage{unicode-math}
\setmainfont{Latin Modern Roman}
\newcommand\blurb{%
  abcd \quad ABCD \quad \gamma\delta\phi\psi\omega 
  \quad \Gamma\Delta\Phi\Psi\Omega}

\begin{document}
Four math styles:

$\begin{array}{@{} ll @{}}
\toprule
$TeX$     & \setmathfont{Latin Modern Math}[math-style=TeX]\blurb \\
$ISO$     & \setmathfont{Latin Modern Math}[math-style=ISO]\blurb \\
$french$  & \setmathfont{Latin Modern Math}[math-style=french]\blurb \\
$upright$ & \setmathfont{Latin Modern Math}[math-style=upright]\blurb \\
\bottomrule
\end{array}$
\end{document}

Answer 2

If your text is entirely in french you are better off with the frenchmath package which implements all french-specific math typesetting.

Answer 3

The newtxmath package has a frenchmath option. newtx is a Times-style font, but also supports libertine, minion, stix2, and other math fonts. newtx is also compatible with LuaLaTeX and XeTeX (see details in package documentation).

\documentclass[11pt]{amsart}
\usepackage{newtxtext}
\usepackage[frenchmath]{newtxmath}

\begin{document}

\[ \Phi(u) = \frac{1}{\sqrt{2\pi}} \int_0^\infty e^{-t^2/2} \, dt \]

\end{document}