\HeaderA{sum}{Sum of Vector Elements}{sum}
\keyword{arith}{sum}
\begin{Description}\relax
\code{sum} returns the sum of all the values
present in its arguments.
\end{Description}
\begin{Usage}
\begin{verbatim}
sum(..., na.rm = FALSE)
\end{verbatim}
\end{Usage}
\begin{Arguments}
\begin{ldescription}
\item[\code{...}] numeric or complex or logical vectors.
\item[\code{na.rm}] logical.  Should missing values be removed?
\end{ldescription}
\end{Arguments}
\begin{Details}\relax
This is a generic function: methods can be defined for it
directly or via the \code{\LinkA{Summary}{Summary}} group generic.
For this to work properly, the arguments \code{...} should be
unnamed, and dispatch is on the first argument.

If \code{na.rm} is \code{FALSE} an \code{NA}
value in any of the arguments will cause
a value of \code{NA} to be returned, otherwise
\code{NA} values are ignored.

Logical true values are regarded as one, false values as zero.
For historical reasons, \code{NULL} is accepted and treated as if it
were \code{integer(0)}.
\end{Details}
\begin{Value}
The sum. If all of \code{...} are of type integer or logical, then
the sum is integer, and in that case the result will be \code{NA} (with a
warning) if integer overflow occurs.  Otherwise it is a length-one
numeric or complex vector.

\strong{NB:} the sum of an empty set is zero, by definition.
\end{Value}
\begin{Section}{S4 methods}
This is part of the S4 \code{\LinkA{Summary}{Summary}}
group generic.  Methods for it must use the signature
\code{x, ..., na.rm}.
\end{Section}
\begin{References}\relax
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988)
\emph{The New S Language}.
Wadsworth \& Brooks/Cole.
\end{References}

