# Bold math letters with mathptmx package

I'm using the package mathptmx for my thesis (I preferred its fonts over newtxtext, newtxmath), but I'm having some troubles with bold math symbols.

In particular, I'm trying to get a bold X letter (in Euler Script Font) and a bold \Sigma as in figure (the ones circled in green), but I can't find a way to get both at the same time: if I use \boldsymbol I get the X and not the \Sigma, if I use \bm from the bm package I get the \Sigma and not the X!

Any help? I tried a few other options suggested in other posts, but with no luck... If the only option is to use newtxmath, is there at least a way to get the X non-slanted? Thanks!

\documentclass[11pt,a4paper,final]{book}
\usepackage{amsmath,amsfonts,amsthm,amssymb}
%\usepackage{bm}
\usepackage[mathscr]{eucal}
\usepackage{mathptmx}
%\usepackage{newtxtext,newtxmath}

\begin{document}

$\boldsymbol{\mathscr{X}}$
$\boldsymbol{\Sigma}$

%$\bm{\mathscr{X}}$
%$\bm{\Sigma}$

\end{document}


newtxmath has an option uprightscript which changes the \mathscr, but the definition is a bit curious and \mathscr errors inside \bm. But you could simply switch the order of the package loading then eucal will work:

\documentclass{book}
\usepackage{amsmath,amsfonts,amsthm,amssymb}
\usepackage{newtxtext}
\usepackage{newtxmath}
\usepackage[mathscr]{eucal}
\usepackage{bm}

\begin{document}

$\mathscr{X} \bm{\mathscr{X}}$
$\bm{\Sigma}$

\end{document}


• Thanks! I also noticed that including the package mathpazo, then \boldsymbol{\Sigma} works also with mathptmx fonts. Feb 29 '20 at 17:25