\begin{Schunk}
\begin{Sinput}
 x <- c(55, 2, 3, 3, 4)
 x
\end{Sinput}
\begin{Soutput}
[1] 55  2  3  3  4
\end{Soutput}
\begin{Sinput}
 is.double(x)
\end{Sinput}
\begin{Soutput}
[1] TRUE
\end{Soutput}
\begin{Sinput}
 is.integer(x)
\end{Sinput}
\begin{Soutput}
[1] FALSE
\end{Soutput}
\end{Schunk}
