This question was discussed here previously, but no answer is provided.
Greek letters are made bold using \boldsymbol
, however they do not look bold at all compared to bold Roman letters, particularly they are within the text and if the text is also Roman.
Consider the following MWE:
\documentclass[]{article}
\usepackage{amsmath}
\usepackage{amssymb}
%\usepackage{upgreek}
\usepackage{newtxtext,newtxmath}
\usepackage[]{bm}
\begin{document}
\noindent
Bold Roman: $\textbf{M}$, $\textbf{a}$, $xyz$. These look OK.\\
Bold Greek: $\boldsymbol{\uppsi}xyz\boldsymbol{\psi}$. They do not look bold at all.
\end{document}
and the result is
Also consider the default font:
\documentclass[]{article}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{upgreek}
%\usepackage{newtxtext,newtxmath}
\usepackage[]{bm}
\begin{document}
\noindent
Bold Roman: $\textbf{M}$, $\textbf{a}$, $xyz$. These look OK.\\
Bold Greek: $\boldsymbol{\uppsi}xyz\boldsymbol{\psi}$. These are a little bit better but still not bold.
\end{document}
and the result is
Edit:
Here is an example text to see the characters better. To me, Roman characters are immediately catching the eye as bold, but not the Greek letters:
Is there a way to have "real" bold Greek letters?
Edit (based on David's comments):
Use of \pmb
with Roman text (second line):
Use of \pmb
with default text (second line):
Edit:
I have added Troys suggestion below. I think this look gives immeadiate impression of a matrix.
Best Answer
A nice solution adapted from another question:
You can modify the line width to your liking to make the letters more/less bold.