# Bold italic vectors

I am trying to display vectors as bold and italic. The command \mathbf sets the letters non-italic. I also googled a bit and stumbled upon \mathbf{\em y} or \mathbfit{y}, which all didn't work.

I hope someone can help me on this.

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I've marked your inline code with backticks . (You don't have to sign with your name since it automatically appears in the lower right corner of your post.) – Hendrik Vogt Mar 28 '11 at 8:30

It depends on the math font, but the bm package can handle most of them. The usage is then $\bm{y}$

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It does! Thanks :) – Alexx Hardt Mar 28 '11 at 8:24
This works. But it is not working within multicolumn environment like the following case, \multicolumn{2}{c}{$\bm{a\:(\si{\angstrom})}$} but it works for \multicolumn{2}{c}{$\bm{\alpha_T\; (K^{-1})}$}. How to solve this? – cosmicraga Sep 12 '13 at 5:30

There is also \boldsymbol{} from the package amsbsy (loaded by amsmath). See \bm package versus \boldsymbol for a discussion of the advantages and disadvantages of each command.

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The answer depends on the math fonts you are actually using. For the standard fonts and as long as you use only letters and numbers this should work:

\documentclass{scrartcl}
\DeclareMathAlphabet      {\mathbfit}{OML}{cmm}{b}{it}

\begin{document}
$a=\mathbfit{a}$
\end{document}

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What I did, is to declare my own command for a vector, well its pretty basic, but you can add other features, like an arrow.

\newcommand{\vect}[1]{\boldsymbol{#1}}


And the usage:

\vect{X} = \left[x_1,x_2,\ldots,x_n \right]^T
`

returning:

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This is already covered by another answer... – Werner May 8 '14 at 19:22
Yes, I took the idea from kawahara.ca/latex-bold-vector-and-arrow-vectors. Sorry I didn't point that out. – Jose Yovany Luis Garcia May 9 '14 at 16:03