\begin{Schunk}
\begin{Sinput}
 X <- matrix(1:24, nrow = 4, ncol = 6, byrow = FALSE, dimnames = list(NULL, letters[1:6]))
 X
\end{Sinput}
\begin{Soutput}
     a b  c  d  e  f
[1,] 1 5  9 13 17 21
[2,] 2 6 10 14 18 22
[3,] 3 7 11 15 19 23
[4,] 4 8 12 16 20 24
\end{Soutput}
\end{Schunk}
