\begin{Schunk}
\begin{Sinput}
 X[1:5 , c("Den", "SD")]
\end{Sinput}
\begin{Soutput}
     Den SD
[1,]   1 19
[2,]   2 20
[3,]   3 21
[4,]   4 22
[5,]   5 23
\end{Soutput}
\end{Schunk}
