Is there any package that makes the math symbols with blackboard bold style?
For example, I want to have $mathbb{\leq}$
[Tex/LaTex] greater equal sign \leq in blackboard bold style
blackboard;
Related Solutions
This doesn't exactly answer your question (how to use bbold with AMS's black board bold characters). I believe that would require some TeX incantations.
A cheaper work around is to use either the package bbm or the package doublestroke. The former defines the \mathbbm command and the latter uses the \mathds command, so they don't conflict with the AMS \mathbb. Also asthetically I prefer the bbm fonts over bbold since the latter is sans serif, which doesn't quite fit in right against the AMS serifed fonts.
Getting the definition of the font from fourier is easy; with a little trial and error one can also get the right magnification factor.
\documentclass{article}
\usepackage{cmbright}
%%% taken from fourier.sty
\DeclareFontFamily{U}{futm}{}
\DeclareFontShape{U}{futm}{m}{n}{
<-> s * [.97534] fourier-bb % but changing the magnification factor
}{}
\DeclareMathAlphabet{\mathbb}{U}{futm}{m}{n}
\begin{document}
$-3\in\mathbb{Z}\subseteq\mathbb{Q}\ne Q$
\texttt{\sbox0{$Q$}\the\ht0}
\texttt{\sbox0{$\mathbb{Q}$}\the\ht0}
\end{document}
The last two lines show that the heights match (up to 0.00001pt).
For the STIX fonts the procedure is similar.
\documentclass{article}
\usepackage{cmbright}
%% taken from the STIX font distribution
\DeclareFontEncoding{LS1}{}{}
\DeclareFontSubstitution{LS1}{stix}{m}{n}
\DeclareFontFamily{LS1}{stixbb}{\skewchar\font127 }
\DeclareFontShape{LS1}{stixbb}{m}{n} {<-> s*[1.032631] stix-mathbb}{}
\DeclareFontShape{LS1}{stixbb}{b}{n} {<-> s*[1.032631] stix-mathbb-bold}{}
\DeclareMathAlphabet{\mathbb}{LS1}{stixbb}{m}{n}
\SetMathAlphabet{\mathbb}{bold}{LS1}{stixbb}{b}{n}
\begin{document}
$-3\in\mathbb{Z}\subseteq\mathbb{Q}\ne Q$
\texttt{\sbox0{$Q$}\the\ht0}
\texttt{\sbox0{$\mathbb{Q}$}\the\ht0}
\end{document}
Best Answer
If you are using pdftex, then you can use
\pdfliterallike this:If you need different sizes in
\scriptstyleandscriptscriptstylethen you use this modification: