Bold math: Automatic choice between \mathbf and \boldsymbol for Latin and Greek symbols?

Question

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.)

Answer 1

You can use both commands together and define something like

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

which should work for most cases.

Answer 2

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}

Answer 3

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.

Answer 4

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)