latex中希腊字母字体加粗

How to bold Greek letter in latex?

1. \mathbf{} works for general letter, but not work for Greek letter. If we want to bold Greek letter in latex, we can use \bm{*} or \boldsymbol{*}

For example, \bm{\sigma} \boldsymbol{\beta}.

\documentclass[paper=a4, fontsize=12pt]{article} % A4 paper and 11pt

 \usepackage{amsmath,amsfonts,amsthm,bm} % 

 

\begin{align*}(\mathbf{n}\cdot \bm{\sigma}) \sigma&=\mathbf{0}

\end{align*}

We will get