Bold instead of bold extended for \boldmath

Alas, yet another question on font selection in mathematics.

I want to avoid bold extended and use bold instead. My main font is computer modern. For text, I managed to change the appearance of bold with the help of this question. Also, changing the font for \mathbf wasn't to hard. But how can I make \bm or \boldmath match the rest of the fonts?

M(n)WE:

\documentclass{scrartcl}
\usepackage{bm}
% Bold in text.
\renewcommand{\bfdefault}{b}
% Bold in \mathbf
\DeclareMathAlphabet{\mathbf}{OT1}{lmr}{b}{n}
\DeclareMathAlphabet{\mathbfit}{OT1}{lmr}{b}{it}
\DeclareMathAlphabet{\mathbxit}{OT1}{lmr}{bx}{it}

\begin{document}
\begin{itemize}
\item Text:
\textbf{bold BOLD}
\item \texttt{mathbf}:
$\mathbf{bold BOLD}$
\item \texttt{mathbfit}:
$\mathbfit{bold BOLD}$
\item \texttt{mathbxit}:
$\mathbxit{bold BOLD}$
\item \texttt{bm}:
$\bm{bold BOLD}$
\item \texttt{boldmath}:
{\boldmath $bold BOLD$.}
\end{itemize}
\end{document}


The issue is that the last two examples show much wider characters than the other examples. In fact, even wider than in the \mathbxit-example.

How can I get the same bold-non-extended letters in \boldmath? Plus: is there a non-extend bold version of \mathcal-letters?

• the fact that \bm outside math mode is not raising an error is an oversight, it is not intended to do work in that context. – David Carlisle Feb 10 at 10:44
• your final two examples are not clear, you are making bold roman use b not bx, but in the bold math you are using math italic and not showing an example of \mathrm the math italic letters are by default \SetSymbolFont{letters} {bold}{OML}{cmm} {b}{it} so already using b not bx – David Carlisle Feb 10 at 10:49
• @DavidCarlisle Please consider my edit. I hope that makes clearer what I want to do. – Bubaya Feb 10 at 11:23
• but you should compare the bold math italic against the normal weight math italic (which you are not showing) math italic has wide sidebearings so adjacent letters look like a product of variables not a word. – David Carlisle Feb 10 at 11:25
• @DavidCarlisle The letter spacing is not what I am confused about, but about the fact that the "O" in the bm-example is wider than the "O" in the \mathbxit-example (at least, it seems), and both are much wider than the mathbfit-O. – Bubaya Feb 10 at 11:28

\SetSymbolFont{operators}{bold}{OT1}{cmr} {b}{n}

Thi swill affect operators like \log and \mathrm generally and make it use bold rather than bold extended.
• @Bubaya your example document doesn't use \log or \mathrm in the scope of \boldmath – David Carlisle Feb 10 at 10:50
• OK, now I understand what this command achieves, at least. Then it seems that \SetSymbolFont{letters}{bold}{OT1}{lmr}{b}{it} works for italics (strangely, not for cmr?). What is necessary for bm to make it use non-extended letters? – Bubaya Feb 10 at 11:24