Why do numbers in mathnormal not match numbers without it?

Question

Why do numbers typeset with mathnormal{...} not give the same result as numbers typeset without it? The documentation here leads me to think they should be the same. I've searched this site and the closest question I've found is this one but this specific issue is never addressed.  I don't need a fix; I only want to know why the difference exists.
MWE:
documentclass{article}

begin{document}
(0123456789)

( mathnormal{0123456789} )
end{document}

David Carlisle · Accepted Answer

math mode consists (in classic TeX) of 16 math font families and each character is assigned a default family and optional allowed to vary the family in the scope of a command like mathbf or mathnormal.
In the default setup digits come from the operator family (normally upright roman font) but mathnormal forces the default math italic font used for letters and that is where the old style numbers are in the default tex encoding.

Marijn · Answer

As you can see in the Font Guide (on page 11), mathnormal uses the cmm font family. This stands for Computer Modern Math Italic (page 4). As David explained, numbers in regular math are taken from the operators family, which is cmr (Computer Modern Roman).
With the fonttable package you can see the glyphs for the different families, using the attributes from the table on page 11 of the Font Guide as arguments for the xfonttable command. MWE:
documentclass{article}
usepackage{fonttable}
begin{document}
xfonttable{OT1}{cmr}{m}{n}
xfonttable{OML}{cmm}{m}{it}
end{document}

cmr numbers:

cmm numbers:

Cicada · Answer

Package-writing and Unicode fonts add further overlays and permutations to the conventions:

MWE
documentclass{article}
usepackage{xcolor}

usepackage{unicode-math}
setmainfont{Noto Sans}[Colour=red]
setmathfont{XITS Math}[Colour=blue]
begin{document}

0123456789 abc ABC αβγ

(0123456789 abc ABC αβγ)

( mathnormal{0123456789 αβγ} αβγ)

( mathrm{0123456789 αβγ} αβγ)

( textrm{0123456789 αβγ} αβγ)

( mathit{0123456789 αβγ} αβγ)

end{document}

Why do numbers in mathnormal not match numbers without it?

3 Answers

Add your own answers!

Ask a Question