# Fontspec changes the bold math

I wish the A, B and C of the matrices defined as follow were written using the default computer modern font. I'm using the fontspec package with LuaLaTeX, but when I set the main font it also changes the math bold font. Here's an excerpt of my document:

\documentclass[12pt,a4paper]{report}

\usepackage{polyglossia}
\setdefaultlanguage{english}
\disablehyphenation

\usepackage[
hmarginratio = 1:1,
left = 3cm,
right = 2cm,
top = 3cm,
bottom = 2cm
]{geometry}

\usepackage{fontspec}
\setmainfont{Arno Pro}

\usepackage{amsmath}
\usepackage{lipsum}

\begin{document}

\lipsum[1]

\begin{center}
${\bf A}_{2\times 3}=\begin{pmatrix} 1 & 2 & 3 \\ 4 & 5 & 6 \end{pmatrix} % \hspace{.5cm} % {\bf B}_{4\times 3}=\begin{bmatrix} 1 & 2 & 3 \\ 4 & 5 & 6 \\ 7 & 8 & 9 \\ 1 & 2 & 3 \end{bmatrix} % \hspace{.5cm} % {\bf C}_{2\times 2}=\begin{Vmatrix} 1 & 2 \\ 3 & 4 \end{Vmatrix}$
\end{center}

\lipsum[2]

\end{document}


As you can see the bold math font is not the computer modern but the numbers are. Although both of them are inside the math environment.

• Don't use \bf. See tex.stackexchange.com/q/516/35864 and tex.stackexchange.com/q/15361/35864. \mathbf seems more appropriate here. But I'm not sure if this solves your problem. But even if not, you should definitely not be using \bf any more anywhere. – moewe May 31 '18 at 13:53
• Use \usepackage[no-math]{fontspec} if you don't want fontspec to interfere. – Ulrike Fischer May 31 '18 at 13:54
• I tried it, but i get the following error: ! LaTeX Error: Option clash for package fontspec. See the LaTeX manual or LaTeX Companion for explanation. Type H <return> for immediate help. ... l.16 \setmainfont {Arno Pro} The package fontspec has already been loaded with options: [] There has now been an attempt to load it with options [no-math] Adding the global options: ,no-math to your \documentclass declaration may fix this. Try typing <return> to proceed. – Levy May 31 '18 at 13:58
• Re the option clash: Load fontspec before polyglossia. – moewe May 31 '18 at 14:02
• In the MWE things work for me (with Linux Libertine instead of Arno Pro, but that should be irrelevant) if I load \usepackage[no-math]{fontspec} before polyglossia and use \mathbf. – moewe May 31 '18 at 14:06

With the help of the members @moewe and @Ulrike Fischer in the comments I loaded the fontspec package before the polyglossia with the option [no-math]and also changed the {\bf } to \mathbf{}.