I want to have a product sign analogously to $A \amalg B$. I tried $A \Pi B$, but as $\Pi$ isn't a binary operator, this does not look that good.
Can you help me?
2 Answers
Use \mathbin to fix the spacing issue.
\documentclass{article}
\newcommand*\productop{\mathbin{\Pi}}
\begin{document}
\[ a \amalg b \qquad a \productop b\]
\end{document}
answered Jul 31, 2013 at 9:05
Another solution is to rotate 180° the symbol \amalg (requires graphicx) to get exactly the same symbol upside down:
\documentclass{article}
\usepackage{graphicx}
\newcommand{\invamalg}{\mathbin{\rotatebox[origin=c]{180}{$\amalg$}}}
\begin{document}
\[ A \amalg B \qquad A \invamalg B\]
\end{document}
To get a size changing symbol you can load the amsmath package and modify the \newcommand line as follows (thanks to egreg for the suggestion):
\newcommand{\invamalg}{\mathbin{\text{\rotatebox[origin=c]{180}{$\amalg$}}}}
In this way you can use the new defined command even in subscripts and superscripts. The following MWE
\documentclass{article}
\usepackage{amsmath}
\usepackage{graphicx}
\newcommand{\invamalg}{\mathbin{\text{\rotatebox[origin=c]{180}{$\amalg$}}}}
\begin{document}
\[
A \invamalg B_{A \invamalg B_{A \invamalg B}}
\]
\[
A \amalg B_{A \amalg B_{A \amalg B}}
\]
\end{document}
gives the result:
answered Jul 31, 2013 at 9:17
-
\amalgis slightly different from a reversed\Pi. You can get a size changing symbol by loadingamsmathand putting\rotatebox[...]{180}{...}inside\text.– egregJul 31, 2013 at 9:29 -
With
\mathchoice{\text{...}}you're typesetting the symbol sixteen times instead of the four with the\textmethod and the result is exactly the same (\textalready does\mathchoiceby itself). There's no need to load\mathtoolsin order to have\mathchoice, which is a primitive of TeX.– egregJul 31, 2013 at 11:57 -
\coprod,\prod,\amalg,\Pi. You can find those with my classifier write-math.com