1% File src/library/stats/man/getInitial.Rd
2% Part of the R package, https://www.R-project.org
3% Copyright 1995-2010 R Core Team
4% Distributed under GPL 2 or later
5
6\name{getInitial}
7\encoding{UTF-8}
8\title{Get Initial Parameter Estimates}
9\alias{getInitial}
10\alias{getInitial.default}
11\alias{getInitial.formula}
12\alias{getInitial.selfStart}
13\usage{
14getInitial(object, data, \dots)
15}
16\arguments{
17  \item{object}{a formula or a \code{\link{selfStart}} model that defines a
18    nonlinear regression model}
19  \item{data}{a data frame in which the expressions in the formula or
20    arguments to the \code{selfStart} model can be evaluated}
21  \item{\dots}{optional additional arguments}
22}
23\description{
24  This function evaluates initial parameter estimates for a nonlinear
25  regression model.  If \code{data} is a parameterized data frame or
26  \code{pframe} object, its \code{parameters} attribute is returned.
27  Otherwise the object is examined to see if it contains a call to a
28  \code{selfStart} object whose \code{initial} attribute can be
29  evaluated.
30}
31\value{
32    A named numeric vector or list of starting estimates for the
33    parameters.  The construction of many \code{selfStart} models is such
34    that these "starting" estimates are, in fact, the converged parameter
35    estimates.
36}
37\author{\enc{José}{Jose} Pinheiro and Douglas Bates}
38\seealso{\code{\link{nls}}, \code{\link{selfStart}},
39  \code{\link{selfStart.default}}, \code{\link{selfStart.formula}}.
40  Further,  \code{\link[nlme]{nlsList}} from \CRANpkg{nlme}.
41}
42\examples{
43PurTrt <- Puromycin[ Puromycin$state == "treated", ]
44print(getInitial( rate ~ SSmicmen( conc, Vm, K ), PurTrt ), digits = 3)
45}
46\keyword{models}
47\keyword{nonlinear}
48\keyword{manip}
49