

   getInitial {nls}                             R Documentation

   GGeett IInniittiiaall PPaarraammeetteerr EEssttiimmaatteess

   DDeessccrriippttiioonn::

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

   UUssaaggee::

        getInitial(object, data, ...)

   AArrgguummeennttss::

     object: a formula or a `selfStart' model that defines a
             nonlinear regression model

       data: a data frame in which the expressions in the for-
             mula or arguments to the `selfStart' model can be
             evaluated

        ...: optional additional arguments

   VVaalluuee::

        A named numeric vector or list of starting estimates
        for the parameters.  The construction of many `selfS-
        tart' models is such that these "starting" estimates
        are, in fact, the converged parameter estimates.

   AAuutthhoorr((ss))::

        Jose Pinheiro and Douglas Bates

   SSeeee AAllssoo::

        `nls', `selfStart', `selfStart.default', `selfS-
        tart.formula'

   EExxaammpplleess::

        library(nls)
        data(Puromycin)
        PurTrt <- Puromycin[ Puromycin$state == "treated", ]
        getInitial( rate ~ SSmicmen( conc, Vm, K ), PurTrt )

