get initial parameter estimates

Usage

getInitial(object, data, ...)

Arguments

object a formula or a selfStart model that defines a nonlinear regression model
data a data frame in which the expressions in the formula or arguments to the selfStart model can be evaluated
... optional additional arguments

Description

This function evaluates initial parameter estimates for a nonlinear regression model. If data is a parameterized data frame or pframe object, its parameters attribute is returned. Otherwise the object is examined to see if it contains a call to a selfStart object whose initial attribute can be evaluated.

Value

A named numeric vector of starting estimates for the parameters. The construction of many selfStart models is such that these "starting" estimates are in fact the converged parameter estimates.

Author(s)

Jose Pinheiro and Douglas Bates

See Also

nls,nlsList,selfStart, selfStart.default,selfStart.formula

Examples

library(lme)
data(Puromycin)
PurTrt <- Puromycin[ Puromycin$state == "treated", ]

## check if the response should be vel or rate
getInitial( vel ~ SSmicmen( conc, Vm, K ), PurTrt )


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