67

This is a follow-up to this question.

Suppose you want to denote vectors by upright bold letters; then \mathbf{u} works fine, except that if it's a Greek letter you have to use \boldsymbol{\omega} instead.

Question: Is it possible to define a generic vector command in LaTeX which automatically chooses between \mathbf and \boldsymbol, so that one can write just \vect{u} and \vect{\omega} without having to treat the Greek symbols specially by hand?

(Just to be clear: \newcommand{\vect}[1]{\boldsymbol{#1}} is no good in this situation, since \boldsymbol{u} gives bold italic instead of roman.)

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Hans Lundmark
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4 Answers4

56

You can use both commands together and define something like

\usepackage{bm}
\newcommand{\vect}[1]{\boldsymbol{\mathbf{#1}}}

which should work for most cases.

Juan A. Navarro
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16

The macro

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

does not work with mathtime pro lite fonts (and from the comments it appears that it does not work with mathpazo either). Another approach is to simply check if the argument is A-Za-z.

\usepackage{bm,xstring}

\def\VEC#1%
    {\IfSubStr{ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz}{#1}
        {\mathbf{#1}}
        {\bm{#1}}}

This is inefficient since it performs the substring check for each execution. One could define macros \VEC@A, \VEC@B etc (using a simple loop), and then check do

\def\VEC#1%
    {\ifcsname VEC@#1\endcsname
        \mathbf{#1}%
     \else
         \bm{#1}%
     \fi}
Aditya
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10

Although this doesn't answer your question, have you tried using the bm package? Then $\bm{\omega}$ gives a bold omega, $\bm{u}$ gives a bold (math italic) u, and $\bm{\mathrm{u}}$ a bold roman u.

Konrad Swanepoel
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    Indeed, defining something like \newcommand{\vect}[1]{\boldsymbol{\mathbf{#1}}} would do the trick. – Juan A. Navarro Sep 27 '10 at 18:55
  • @Juan: why not make an answer out of your comment? – Konrad Swanepoel Sep 27 '10 at 19:02
  • Hmm.. because I thought it was pretty much the same (i.e. use both commands together), but maybe not? – Juan A. Navarro Sep 27 '10 at 19:07
  • @Juan: Thanks, that works! Except that I'm getting weird errors from an \underbrace in a file where I tried it: "Use of \reserved@a doesn't match its definition." and " LaTeX Error: Too many math alphabets used in version bold." Unfortunately that particular formula works fine in a file on its own, so I'm having trouble producing a minimal example where it fails... – Hans Lundmark Sep 27 '10 at 19:41
  • \newcommand*\vect[1]{\mathbf{\bm{#1}}} works. – TH. Sep 27 '10 at 20:36
  • @TH.: Yes, that works too (with Computer Modern). However, both your suggestion and Juan's fail when used with the mathpazo package... (\vect{\omega} gives a bold exclamation mark.) – Hans Lundmark Sep 28 '10 at 12:08
  • @Hans Lundmark: Indeed. I'm afraid I have no insights. Fonts are mysterious to me. – TH. Sep 28 '10 at 20:32
  • \boldsymbol{...} on its own doesn't seem to do anything (both \omega and u stay unchanged). And \mathbf{\omega} on its own already gives the exclamation mark when using mathpazo. – Konrad Swanepoel Sep 28 '10 at 21:06
5

I just wanted to add: if you want upright greek characters, use

\usepackage{upgreek}

Combining this with the above answers, you can then e.g. do

\vect{\upmu}

to get a bold upright mu.

(sourced from here)

JHBonarius
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