Htydjtk

Can someone tell me what I am doing wrong or simply tell me how I can use the coptic letter "Me" in math mode?

I want to use a coptic letter in a mathematical expression in my TeX document. From my very limited understanding of how all these things work I read that "XeTeX and LuaTeX support Unicode".

Not entirely sure what that actually means I came across the (XeTeX and LuaTex) commands char"xxxx, symbol{xxxx} and ^^^^xxxx only to find out that I have no idea how to actually use them. I tried out this little code example:

documentclass{article}

usepackage{fontspec}

usepackage{unicode-math}



begin{document}

Trying to display the symbols ©, ❤ and the coptic letter "Me": \

char"00a9, char"2764, char"2C98  \

par

And now again in math mode: \

$char"00a9, char"2764, char"2C98 $

end{document}

Which yielded the following output:

Similarly, with the second command I get:

Trying to display the symbols ©, ❤ and the coptic letter "Me": \

symbol{00a9}, symbol{2764}, symbol{2C98} \

par

And now again in math mode: \

$symbol{00a9}, symbol{2764}, symbol{2C98}$ 

and for the last one I even get an error message:

Trying to display the symbols ©, ❤ and the coptic letter "Me": \

^^^^00a9, ^^^^2764, ^^^^2C98 \

par

And now again in math mode: \

$^^^^00a9, ^^^^2764, ^^^^2C98$

yields

! ^^^^ needs four hex digits. ^^^^ 00a9, ^^^^2764, ^

You need a font that has the character. On my machine Firefox used Segoe UI Symbol to display this, so I used the same in lualatex:

documentclass{article}

usepackage{fontspec}

usepackage{amsmath}

usepackage{unicode-math}

newfontfamilyzzzz{Segoe UI Symbol}



begin{document}

Trying to display the symbols ©, ❤ and the coptic letter "Me" {zzzz(Ⲙ)}: 





And now again in math mode: \

$ text{zzzz Ⲙ}  $



end{document}

Note that char"00a9 will try to print the character in slot 0 and then “a9”, because TeX hexadecimal numeric notation requires uppercase letters. To the contrary, the ^^^^ notation requires lowercase letters.

So either char"00A9 or ^^^^00a9. They can't be mixed. There's a big difference among the two: the former is an instruction to print the glyph in position "00A9 of the current font, the latter is the character U+00A9.

Now, if the current font, be it in text mode or math mode (what's the current font in math mode depends on many factors) doesn't contain a glyph at a certain position, no fallback is used in XeLaTeX or LuaLaTeX and so you end up with no glyph (or a placeholder).

In order to obtain a glyph in a different font, you have to declare what font to use.

At this point, if you want to use the Coptic letter Me in math, you can even declare it as a math symbol.

documentclass{article}

usepackage{unicode-math}



% use a font which has the glyph

newfontfamily{copticfont}{FreeSerif}[

  NFSSFamily=coptic,

]



DeclareSymbolFont{coptic}{TU}{coptic}{m}{n}

% need to use a low level declaration

UmathchardefMe="0 symcoptic "2C98



begin{document}



$Me+Me$



end{document}

You can even be bold and use the symbol itself in math:

documentclass{article}

usepackage{unicode-math}



% use a font which has the glyph

newfontfamily{copticfont}{FreeSerif}[

  NFSSFamily=coptic,

]



DeclareSymbolFont{coptic}{TU}{coptic}{m}{n}

% need to use a low level declaration

UmathchardefMe="0 symcoptic "2C98

Umathcode`Ⲙ="0 symcoptic "2C98



begin{document}



$Me+Me$



$Ⲙ+Ⲙ$



end{document}