How to type a primitive sum (a summation sign with "*" sign at the top right corner) inside the equation?
Primitive sum in latex
math-operators
Related Solutions
Here's an alternative that uses TikZ. With the amsmath and tikz packages loaded, put the following in your preamble
\newcommand\constructosum[3]{%
\begin{tikzpicture}[baseline=(char.base), inner sep=0, outer sep=0]
\draw (#1,0) circle (#2);
\node (char) at (0,0) {$#3\sum$}; % Want to define a second symbol for inline...
\end{tikzpicture}%
}
\newcommand{\modtwosum}{\mathop{\mathchoice
{\constructosum{-0.3ex}{0.1}{\displaystyle}}
{\constructosum{-0.3ex}{0.06}{\textstyle}}
{\constructosum{-0.2ex}{0.04}{\scriptstyle}}
{\constructosum{-0.15ex}{0.03}{\scriptscriptstyle}}
}\displaylimits
}
This defines four operators corresponding to display style math environments, inline math, script size math and script script size math in that order. Each has a coordinate for the loop which may be adjusted, and a size for the loop. For example the display style version has
\constructosum{-0.3ex}{0.1}{\displaystyle}
which places the loop at -0.3ex (moves it horizontally backwards a bit) with a radius of 0.1cm. To use it, simply use the new operator \modtwosum inside any math environment. e.g.
\[
G=\modtwosum_a^b H
\]
A demo of this operator in each of the four situations that may occur:
Thanks goes to egreg for pointing out that I could reduce the original version of this with a helper \newcommand to contain the TikZ code.
Use \mathop{\mathbb{E}} to get math operator spacing and limits behaviour. Or \mathop{{}\mathbb{E}} If you want E to remain on the baseline.
Best Answer
This can be done with the
\sidesetcommandThe empty braces in
\sidesetare needed because\sidesetallows for sub- and superscripts on the left side of the operator also.