I would like to fulfill a matrix with multido (because I will have tons of matrices to write). I would like to do something like this but that does not work
\documentclass[11pt]{article} \usepackage{amsmath,multido,ifthen} \begin{document} $$\begin{pMatrix}\multido{\i=1+1}{13}{% \multido{\I=1+1}{7}{% 1\ifthenelse{\I<7}{&}{\\}}} \end{pmatrix}$$ \end{document} If someone has a good idea...

\[and\]and not$$. See here.