boldfontsitalicmath-modesans-serif
And they look differently?
I'm trying to typeset iso conform (vectors bold italic and tensors sans serif bold italic).
Mechanical stress $\sigma$ is a tensor, but I also want to typeset the normal stress, which is the tensor multiplied by the unit normal $\mathbf n$ and hence, a vector as well.
I tried bm (results in serif bold \sigma) or isomath (error font shape OML/ptm/bx/it undefined).
As I understand your question, you would like the \bm command to always typeset its contents in slanted style, whether in ordinary, i.e., serif, math mode or in the sansmath environment. The following modified version of your MWE achieves this objective.
Relative to your code, I've made the following three changes: (a) The sansmath package is now loaded with the T1 option; (b) the \SetMathAlphabet{\mathsfbf}...{bx}{sl} command tells LaTeX to use a slanted font in bold-math mode; (c) the sansmath environment is augmented so that \bm will typeset its argument the way that \mathsfbf does. (I say "augmented" rather than "patched" because I believe that the sansmath package predates the bm package. Hence, the sansmath package couldn't make allowance for the emergence of the subsequent \bm command, right?)
A word of caution: This quick fix lets \bm operate, as expected, on lower- and uppercase Latin letters in the sansmath environment. However, some of the other "magic" of the bm package, which lets it operate on Greek letters and math symbols as well, is not preserved by this method. To set Greek letters and math symbols in bold in the sansmath environment, you'll have to use the \boldsymbol command. (By the way, AFAIK the Latin Modern font family doesn't provide separate sans-serif math-mode Greek letters, whether regular weight or bold. Therefore, if you use Greek letters in the sansmath environment, you'll get the ordinary math-mode Greek letters, which may look wrong in a sans-serif environment. If you must have sans-serif Greek math-mode letters in your document, you should probably use xelatex and employ a specialized math font that does provide this feature.)
\documentclass{scrartcl}
\usepackage{lmodern,bm}
\usepackage[T1]{sansmath}
\SetMathAlphabet{\mathsfbf}{sans}{\sansmathencoding}{\sfdefault}{bx}{sl}
\usepackage{etoolbox}
\AtBeginEnvironment{sansmath}{\let\bm\mathsfbf}{}{}
\begin{document}
Serif math:
$\bm{d} = (d_1, d_2)$
$\mathbf{d} = (d_1, d_2)$
\textsf{Sans-serif math:}
\begin{sansmath}
$\bm{d} = (d_1, d_2)$
$\mathbf{d} = (d_1, d_2)$
\end{sansmath}
\end{document}
I suggest you take a look at Michael Sharpe's mathalfa (the spelling "mathalpha" works too) package. In the package's user guide, the author lists five "hollowed-out" and fourteen [!] "geometric" variants of blackboard-bold fonts. (Note that not all of the underlying fonts are free.) I trust that one or more of the math blackboard board fonts listed and/or made available through the mathalfa package will meet your needs. (I'm afraid I don't have access to German-language math textbooks.)
A big plus of using the mathalfa package is that you can "mix and match" various math alphabets (blackboard bold, caligraphic, curly, script, fraktur, etc) with ease. Excerpting from the README file that comes with the mathalfa package:
This package provides a standard means of setting math alphabets associated with the macros \mathcal, \mathbb, \mathfrak and \mathscr and, where available, their bold counterparts \mathbcal, \mathbbb, \mathbfrak and \mathbscr.
It mostly bypasses the usual fd and sty files used to load these alphabets in order to allow each to be scaled independently and without silently quantizing the sizes.
Best Answer
If you have the option of using
lualatexthenunicode-mathprovides access to such characters:Tex Gyre Termes Mathis quite new, an older font isTex Gyre Pagella Math, the name has just changed fromTG Pagella Math:Alternatively there are the
XITSfonts, where the distinction is less clear: