\HeaderA{is.multiple}{Find multiple-charged polypeptides.}{is.multiple}
\keyword{arith}{is.multiple}
\begin{Description}\relax
For each of the polypeptides in a vector, find its multiple-charged species in the vector.
\end{Description}
\begin{Usage}
\begin{verbatim}
is.multiple(v, k = 2, eps = 0.003)
\end{verbatim}
\end{Usage}
\begin{Arguments}
\begin{ldescription}
\item[\code{v}] a vector of polypeptides.
\item[\code{k}] a vector of integers, that is, multiples of interest.
\item[\code{eps}] a user specified precision of peak position.
\end{ldescription}
\end{Arguments}
\begin{Details}\relax
If abs(v-k*u)/v <= eps, then v is considered to be u with
k charges.
\end{Details}
\begin{Value}
A list named with the m/z values of polypeptides who have
multiple-charged species; each component is a named vector
of polypeptides with number of charges as names.
\end{Value}
\begin{Examples}
\begin{ExampleCode}
bmks <- c(2360.25, 2666.34, 3055.72, 3058.04, 
3776.94, 3778.24, 3779.53, 4712.37,7559.76, 4587.03, 
4589.88, 9155.59, 13298.7)
is.multiple(bmks, k=2:5)
\end{ExampleCode}
\end{Examples}

