Frequently Asked Question List for TeX
The issue here is complicated by the fact that \mathbf
(the
command for setting bold text in TeX maths) affects a select
few mathematical “symbols” (the uppercase Greek letters).
In the default configuration, lower-case Greek letters behave differently from upper-case Greek letters (the lower-case greek letters are in the maths fonts, while the upper-case letters are in the original (OT1-encoded) text fonts).
The Plain TeX solution does work, in a limited way; you set a maths style, before you start an equation; thus
{\boldmath$\theta$}
does the job, but \boldmath
may not be used in maths mode. As a
result, this solution requires that you embed single bold characters
in a text box:
$... \mbox{\boldmath$\theta$} ...$
which then causes problems in superscripts, etc. With
amsmath
loaded,
$... \text{\boldmath$\theta$} ...$
does the trick (and is less bad in regard to superscripts, etc), but is an unsatisfactory solution, too.
These problems may be addressed by using a bold mathematics package.
bm
package, which is part of the LaTeX tools
distribution, defines a command \bm
which may be used anywhere
in maths mode.amsbsy
package (which is part of
amsmath
bundle)
defines a command \boldsymbol
, which (though slightly less
comprehensive than \bm
) covers almost all common cases.All these solutions apply to all mathematical symbols, not merely Greek letters.
FAQ ID: Q-boldgreek