[Tex/LaTex] Bold italic math fonts with unicode-math (xelatex)

Question

I don't understand how to get bold italics fonts with unicode maths.
When I load unicode-maths the bold italics from \boldmaths becomes normal, and \mathbf gives right fonts.

Thank you for your help.

\documentclass[a4paper,11pt]{article}

\usepackage[tuenc]{fontspec}
\usepackage[a4paper]{geometry}
\usepackage[french]{babel}

\usepackage[bold-style=ISO]{unicode-math} %works without this
    \setmathfont{Latin Modern Math}
    \setmathfont[range={\mathscr,\mathbfscr}]{XITS Math}

\begin{document}

$x+y=z$

{\boldmath$x+y=z$}

$\mathbf{x+y=z}$

\end{document}

Answer 1

There is no bold Latin Modern Math font. You could fake it, but I don't believe it's what you want.

You should recall that unicode-math defines \symbf which should be used to get a letter in boldface, rather than \mathbf, which uses the text bold font.

\documentclass[a4paper,11pt]{article}

\usepackage[tuenc]{fontspec}
\usepackage[a4paper]{geometry}
\usepackage[french]{babel}

\usepackage[bold-style=ISO]{unicode-math}                    
\setmathfont{Latin Modern Math}
\setmathfont[range={\mathscr,\mathbfscr}]{XITS Math}

\begin{document}

$x+y=z$

$\symbf{x}+\symbf{y}=\symbf{z}$

\end{document}