\Header{NLSstLfAsymptote}{Horizontal Asymptote on the Left Side}
\methalias{NLSstLfAsymptote.sortedXyData}{NLSstLfAsymptote}
\keyword{manip}{NLSstLfAsymptote}
\begin{Description}\relax
Provide an initial guess at the horizontal asymptote on the left side
(i.e., small values of \code{x}) of the graph of \code{y} versus
\code{x} from the \code{xy} object.  Primarily used within
\code{initial} functions for self-starting nonlinear regression
models.
\end{Description}
\begin{Usage}
\begin{verbatim}
NLSstLfAsymptote(xy)
\end{verbatim}
\end{Usage}
\begin{Arguments}
\begin{ldescription}
\item[\code{xy}] a \code{sortedXyData} object
\end{ldescription}
\end{Arguments}
\begin{Value}
A single numeric value estimating the horizontal asymptote for small
\code{x}.
\end{Value}
\begin{Author}\relax
Jose Pinheiro and Douglas Bates
\end{Author}
\begin{SeeAlso}\relax
\code{\Link{sortedXyData}},
\code{\Link{NLSstClosestX}},
\code{\Link{NLSstRtAsymptote}},
\code{\Link{selfStart}}
\end{SeeAlso}
\begin{Examples}
\begin{ExampleCode}
data( DNase )
DNase.2 <- DNase[ DNase$Run == "2", ]
DN.srt <- sortedXyData( expression(log(conc)), expression(density), DNase.2 )
NLSstLfAsymptote( DN.srt )
\end{ExampleCode}
\end{Examples}

