# How do you produce sign for set multiplication (from old math book) in LaTeX?

I'm reading an old book on Mathematical analysis and in the chapter on sets I found this:

This represents set multiplication and I want to reproduce this in my notes, but can't seem to find a way to do that. How can I do this in LaTeX?

• Use the \DeclareMathOperator command with the proper sign (a scales \times sign here I would say). See for instance: tex.stackexchange.com/questions/50669/… – pluton Sep 8 '13 at 16:24
• \varprod is provided by the packages txfonts and pxfonts. – karlkoeller Sep 8 '13 at 16:37

There is a \varprod operator provided by the packages txfonts/pxfonts and a \bigtimes operator provided by the package mathabx.

Unless you want to load one of the mentioned packages for any other need, I suggest you to "extract" the definition of the symbol from the package and use it as in the following MWE. Choose the one you prefer.

\documentclass{article}

% \varprod
\DeclareSymbolFont{largesymbolsA}{U}{txexa}{m}{n}
\DeclareMathSymbol{\varprod}{\mathop}{largesymbolsA}{16}

% \bigtimes
\DeclareFontFamily{U}{mathx}{\hyphenchar\font45}
\DeclareFontShape{U}{mathx}{m}{n}{
<5> <6> <7> <8> <9> <10>
<10.95> <12> <14.4> <17.28> <20.74> <24.88>
mathx10
}{}
\DeclareSymbolFont{mathx}{U}{mathx}{m}{n}
\DeclareMathSymbol{\bigtimes}{1}{mathx}{"91}

\begin{document}
$\varprod^{N}_{n-1} X_n \quad \bigtimes^{N}_{n-1} X_n$
\end{document}


With unicode-math, you can get it with \bigtimes:

\documentclass{article}
\usepackage{unicode-math}
\begin{document}
$\bigtimes_{n=1}^N X_n$
\end{document}