\Header{numeric}{Numeric Vectors}
\alias{as.numeric}{numeric}
\alias{is.numeric}{numeric}
\keyword{classes}{numeric}
\keyword{attribute}{numeric}
\begin{Usage}
\begin{verbatim}
numeric(length = 0)
as.numeric(x)
is.numeric(x)
\end{verbatim}
\end{Usage}
\begin{Description}
\texttt{numeric} creates a real vector of the specified length.  The
elements of the vector are all equal to \texttt{0}.

\texttt{as.numeric} attempts to coerce its argument to numeric type
(either integer or real).

\texttt{is.numeric} returns \texttt{TRUE} if its argument is of type real
or type integer and \texttt{FALSE} otherwise.\end{Description}
\begin{Note}
\emph{\R\ has no single precision data type.  All real numbers are
stored in double precision format}.

\texttt{as.numeric} for factors yields the codes underlying the factor
levels.\end{Note}
\begin{Examples}
\begin{ExampleCode}
as.numeric(c("2","B"))
as.numeric(factor(5:10))
\end{ExampleCode}
\end{Examples}

