That's in a chapter of my thesis template so I dont need \begin{document}. So in this chapter I wanna make a 12-column bmatrix inside this equation like this:
and thats the code im trying to form it:
\begin{equation}
\left[N\right]
=
\begin{bmatrix}
N_1 & 0 & 0 & N_2 & 0 & 0 & N_3 & 0 & 0 & N_4 & 0 & 0 \\
0 & N_1 & 0 & 0 & N_2 & 0 & 0 & N_3 & 0 & 0 & N_4 & 0 \\
0 & 0 & N_1 & 0 & 0 & N_2 & 0 & 0 & N_3 & 0 & 0 & N_4
\end{bmatrix}
\end{equation}
but I get this error:
Extra alignment tab has been changed to \cr
at the 3 lines after \begin{bmatrix} and I don't know whats the problem.
bmatrixonly handles up to 10 cols, add\setcounter{MaxMatrixCols}{20}to your preamble. – daleif Sep 07 '20 at 10:00