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.


kpfontsandmathdesignboth have options to get French style in math mode. – Feb 12 '14 at 06:32kpfontsmodifies the font andmathdesign, with the appropriateuppercase=uprightandgreeklowercase=uprightoptions didn't work at all (?). I must admit I only skimmed the documentations though. – Idl Feb 12 '14 at 06:50MinionPropackage also has such an option. – Bernard Feb 12 '14 at 09:20mathdesignpossibly some text font needs to be installed likeURW Garamond. But yes bothkpfontsandmathdesignare font packages (kpfontsproviding its own fonts for text and mathematics). – Feb 12 '14 at 12:43