[Tex/LaTex] Bold calligraphic typeface

boldfontsmathcal

I know \mathcal{ABC...}, but can't bold these

Best Answer

You can define your own math alphabet that accesses the Computer Modern symbol font in its bold weight.

\documentclass{article}

\DeclareMathAlphabet\mathbfcal{OMS}{cmsy}{b}{n}

\begin{document}
$\mathcal{A}$ $\mathbfcal{A}$
\end{document}

Example