# Is a cupdot symbol available in amsmath? [duplicate]

I'm looking for a command in amsmath that makes something like \cupdot in MnSymbol (I hope spell it right...).

Look at the picture below:

i.e. a command that puts a dot instead of the "+".

One more thing: I don't want that the dot will be above the cup sign - the dot should be inside the cup.

If the preferred math font does not contain the symbol, it can be provided by putting \cup and \cdot together:

\documentclass{article}
\usepackage{amsmath}

\makeatletter
\providecommand*{\cupdot}{%
\mathbin{%
\mathpalette\@cupdot{}%
}%
}
\newcommand*{\@cupdot}[2]{%
\ooalign{%
$\m@th#1\cup$\cr
\hidewidth$\m@th#1\cdot$\hidewidth
}%
}
\makeatother

\begin{document}
$a\cupdot b$
\end{document}


Remarks:

• \mathbin keeps the spacing of a binary operator (like \cup) for the new symbol.
• The trick with \mathpalette ensures that the symbol adopts its size if used in fractions, subscripts, ...

## Variant with vertically centered dot and \bigcupdot

\documentclass{article}
\usepackage{amsmath}
\usepackage{graphicx}

\makeatletter
\providecommand*{\cupdot}{%
\mathbin{%
\mathpalette\@cupdot{}%
}%
}
\newcommand*{\@cupdot}[2]{%
\ooalign{%
$\m@th#1\cup$\cr
\sbox0{$#1\cup$}%
\dimen@=\ht0 %
\sbox0{$\m@th#1\cdot$}%
\dimen@=.5\dimen@
\hidewidth\raise\dimen@\box0\hidewidth
}%
}

\providecommand*{\bigcupdot}{%
\mathop{%
\vphantom{\bigcup}%
\mathpalette\@bigcupdot{}%
}%
}
\newcommand*{\@bigcupdot}[2]{%
\ooalign{%
$\m@th#1\bigcup$\cr
\sbox0{$#1\bigcup$}%
\dimen@=\ht0 %
\sbox0{\scalebox{2}{$\m@th#1\cdot$}}%
\dimen@=.5\dimen@
\hidewidth\raise\dimen@\box0\hidewidth
}%
}
\makeatother

\begin{document}
$\bigcupdot a\cupdot b$
\end{document}
\documentclass{article}
\usepackage{amsmath}

\makeatletter
\providecommand*{\cupdot}{%
\mathbin{%
\mathpalette\@cupdot{}%
}%
}
\newcommand*{\@cupdot}[2]{%
\ooalign{%
$\m@th#1\cup$\cr
\sbox0{$#1\cup$}%
\dimen@=\ht0 %
\sbox0{$#1\cdot$}%
\dimen@=.5\dimen@
\hidewidth\raise\dimen@\hbox{$\m@th#1\cdot$}\hidewidth
}%
}
\makeatother

\begin{document}
$\bigcupdot_{i=1}^{\infty} a_i\cupdot b$
\end{document}


• Thank you!! Both paragraphs are needed? – heblyx Apr 26 '13 at 22:14
• and what is the command to do it bigger? for a display eq. – heblyx Apr 26 '13 at 22:15
• @YoavFridman The part between \makeatletter and \makeatother inclusively is needed. – Heiko Oberdiek Apr 26 '13 at 22:19
• @YoavFridman The examples show the symbol in displayed equations, do you mean a symbol like \int/\sum/\bigcup? – Heiko Oberdiek Apr 26 '13 at 22:21
• There is an error at your code... I put at Lyx Preamble and it's says that \begin{document} is missing.... – heblyx Apr 26 '13 at 22:22