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.
\pmb
macro in amsmath will print the character 3 times with slight offsets but I'd never do that of (as here) there is a bold font available.\uppsi
and\psi
then the newtxmath one looks like this with the bold characters noticeably bolder than the non bold despite the following text saying they do not look bold.