\Header{double}{Double Precision Vectors}
\alias{as.double}{double}
\alias{as.double.default}{double}
\alias{is.double}{double}
\alias{as.single}{double}
\alias{as.single.default}{double}
\keyword{classes}{double}
\begin{Usage}
\begin{verbatim}
double(length = 0)
as.double(x)
is.double(x)
\end{verbatim}
\end{Usage}
\begin{Value}
\texttt{double} creates a double precision vector of the specified
length.  The elements of the vector are all equal to \texttt{0}.

\texttt{as.double} attempts to coerce its argument to be of double
type.

\texttt{is.double} returns \texttt{TRUE} or \texttt{FALSE} depending on
whether its argument is of double type or not.\end{Value}
\begin{Note}
\emph{\R\ has no single precision data type.  All real numbers are
stored in double precision format}.\end{Note}
\begin{SeeAlso}
\texttt{\Link{integer}}.\end{SeeAlso}
\begin{Examples}
\begin{ExampleCode}
is.double(1)
all(double(3) == 0)
\end{ExampleCode}
\end{Examples}

