# Undefined control sequence for beta symbol list

I would like to give a beta symbol with a sequence of values as below.

\boldsymbol{\beta} = (\beta_1,\beta_2,\dotsc,\beta_n)


output looks promising.

β = (β1, β2, , βn) (1)


But I get an error like

Undefined control sequence.
l.77 \boldsymbol
{\beta} = (\beta_1,\beta_2,\dotsc,\beta_n)
The control sequence at the end of the top line
of your error message was never \def'ed.


• You need to load the amsmath package.
– Mico
Mar 13, 2015 at 22:14
• (1) welcome, (2) always provide full minimal examples so we do not have to guess your preamble (3) load time the bm package and use \bm to mark the bold symbols Mar 13, 2015 at 22:14
• @Mico I've imported it but it doesn't work... Jan 28 at 4:05
• @Mico need to import usepackage bm also \usepackage{amsmath} % for \boldsymbol macro \usepackage{bm} % for \bm macro Jan 28 at 4:07
• @CharlieParker - Please re-read the original posting and then my comment. The original posting contained a \boldsymbol directive -- which "did not work" -- and, importantly, it did not contain a \bm directive. The only non-bizarre way my comment can be construed is that it addresses the OP's complaint by pointing out that it's necessary to load the amsmath package in order to get to use the \boldsymbol directive. Since there was no \bm directive in the OP's code, I saw no need to further point out that it would be necessary to load the bm package in order to activate \bm.
– Mico
Jan 28 at 4:12

To use \boldsymbol (in math mode, of course), you need to load the amsmath package.

Alternatively, load the bm ("bold math") package and write \bm{\beta} (again in math mode, of course).

\documentclass{article}
\usepackage{amsmath} % for \boldsymbol macro
\usepackage{bm}      % for \bm macro
\begin{document}
$\boldsymbol{\beta} = (\beta_1,\beta_2,\dots,\beta_n)$

$\bm{\beta} = (\beta_1,\beta_2,\dots,\beta_n)$
\end{document}

• The manual of amsbsy (loaded by amsmath and providing \boldsymbol) recommends using \bm instead of \boldsymbol. Mar 13, 2015 at 22:27
• @egreg - The manual of the amsmath package provides the same recommendation, while narrowing it a bit, by stating that the bm should be loaded and \bm be used if a user doesn't require the (many!) other facilities of the amsmath package. Of course, if bm is loaded after amsmath, the instruction \let\boldsymbol\bm is executed, and bm's bolding method is used whenever \boldsymbol is typed (as is the case in my MWE...).
– Mico
Mar 14, 2015 at 6:48
• I've imported it but it doesn't work... Jan 28 at 4:05
• @CharlieParker - Please clarify your comment. In particular, what does the first instance of "it" refer to?
– Mico
Jan 28 at 4:21