\begin{array}{col1col2...coln}
column 1 entry & column 2 entry ... & column n entry \\
.
.
.
\end{array}
Math arrays are produced with the array environment. It has a single
mandatory argument describing the number of columns and the alignment
within them. Each column, coln, is specified by a single letter
that tells how items in that row should be formatted.
c - for centred
l - for flushleft
r - for flushright
Column entries must be separated by an &. Column entries may
include other LaTeX commands. Each row of the array must be terminated
with the string \\.