Custom math mode font

fontsfontspecmath-fontsmath-mode

I created a custom font Computer Modern Roman Blackboard Bold, similar to the Computer Modern Roman - italic as the following image:

As you can imagine, I want to implement this font in math-mode such as \cmrbb{hello} or maybe substitute \mathsf alphabet for mine, then rename a new command \cmrbb.

Specifications

I'm using fontspec
I'm using LuaLaTeX
I have some packages like amsmath, amssymb, mathtools (I don't know if it can cause trouble)
I want to use the new font as a simple command like \cmrbb{text} inside math-mode
I'm working currently on Overleaf and have loaded cmrbb.ttf

I have no idea how I can do it, I tried using mathspec but the document doesn't even compile (I think it only works in XeLaTeX).

And just in case there is no incompatibility, I don't use any command for font encoding, and I have already loaded some fonts. I don't know much about fontspec, any additional information to make it easier to implement the solution would be really helpful.

Best Answer

It's not clear if your font is OT1 encoded like the original cmr or TU Unicode encoded, but basically

\DeclareMathAlphabet      {\cmrbb}{OT1}{cmrbb}{m}{n}

\DeclareMathAlphabet      {\cmrbb}{TU}{cmrbb}{m}{n}

together with a suitable fd file if using OT1 and declare the font using \newfontfamily\cmrbbfam[NFSSFamily=cmrbb] if using TU encoded fonts.

An example (produced with xelatex) using some opentype font found on this system, the declarations would be the same for any font.

\documentclass{article}
\usepackage{fontspec}

\newfontfamily\cmrbbfam{Goudy Stout}[NFSSFamily=cmrbb]
\DeclareMathAlphabet      {\cmrbb}{TU}{cmrbb}{m}{n}

\begin{document}


\[
  a=\cmrbb{N}+\cmrbb{xyz} + y
  \]
\end{document}

Related Solutions

[Tex/LaTex] How to change the math italic font in XeTeX/fontspec

If you do not wish to otherwise change your maths symbols, the best solution is to use the mathspec package:

\documentclass{article}
\usepackage{mathspec}
\setallmainfonts(Digits,Latin){Georgia}
\begin{document}
Hello $a+\mathrm{b}=c$
\end{document}

Here, Georgia will be used for the body text and \mathrm, and Georgia Italic will be used for the italic math glyphs.

The unicode-math package (which I kinda wrote) can also do this, but it's somewhat overkill for your purposes and has the additional downside that you need to also load a Unicode mathematics font. Here's an example:

\documentclass{article}
\usepackage{unicode-math}
\setmainfont{Georgia}
\setmathfont{xits-math.otf}
\setmathfont[range=\mathit]{Georgia Italic}
\begin{document}
Hello $a+b=c$
\end{document}

Note that mathspec will not run (yet) on LuaTeX, so if you need a LuaLaTeX solution then you'll need to use unicode-math for now.

[Tex/LaTex] grabbing a single Greek glyph from an alternative font in math mode

You can use a modified version of Importing a single symbol from a different font

\usepackage[T3,T1]{fontenc}
\makeatletter
\newcommand\ipamathsymbol[2][\mathord]{%
  #1{\@ipamathsymbol{#2}}}
\def\@ipamathsymbol#1{\mathchoice
  {\@ipam@thsymbol{#1}\tf@size}
  {\@ipam@thsymbol{#1}\tf@size}
  {\@ipam@thsymbol{#1}\sf@size}
  {\@ipam@thsymbol{#1}\ssf@size}}
\def\@ipam@thsymbol#1#2{%
  \mbox{\fontsize{#2}{#2}\usefont{T3}{cmr}{m}{sl}\symbol{#1}}}
\makeatother
\renewcommand{\gamma}{\ipamathsymbol{71}}

Loading the T3 encoding is necessary, since the tipa fonts are available only in that encoding. Change T1 in OT1 if the latter is your default encoding. I've left the entire infrastructure rather than defining a one shot command, so one can play with other symbols as well; \ipamathsymbol has an optional argument (the math kind of the symbol, default \mathord) and the mandatory argument is the slot number of the chosen glyph.

Specifications

Best Answer

Related Solutions

[Tex/LaTex] How to change the math italic font in XeTeX/fontspec

[Tex/LaTex] grabbing a single Greek glyph from an alternative font in math mode

Related Question