How to write a big cartesian product symbol in MathJax

[Matthias G. Mayer]

This short post is about how to write something like ${\times }_{i\in I}{V}_i$ and $\underset{i\in I}{\times }{V}_i$

MathJax doesn’t allow picture environments so we can’t define a new command that draws a cross. The solution is simple: Enlarge the normal \times command.

Paste this in a math environment at the top of the document:

\newcommand{\bigtimes}{\mathop{\Large\times\normalsize}}

[niplav]

Thank you! I was looking for this.

Then ${+}_{i\in I}{V}_i$, ${\bullet }_{i\in I}{V}_i$, ${\ast }_{i\in I}{V}_i$ can be written via

$\newcommand{\bigplus}{\mathop{\Large+\normalsize}} \bigplus_{i \in I}Vi$
$\newcommand{\bigdot}{\mathop{\Large•\normalsize}} \bigdot_{i \in I}Vi$
$\newcommand{\bigmult}{\mathop{\Large*\normalsize}} \bigmult_{i \in I}Vi$