R: Manipulate a nonlinear model formula.

nlformula {lme4}

R Documentation

Manipulate a nonlinear model formula.

Description

Check and manipulate the formula for a nonlinear model.

Usage

  nlformula(mc)

Arguments

mc

matched call from the calling function. Should have arguments named

formula

a formula of the form resp ~ nlmod ~ meform where resp is an expression for the response, nlmod is the nonlinear model expression and meform is the mixed-effects model formula. resp can be omitted when, e.g., optimizing a design.

data

a data frame in which to evaluate the model function

start

either a numeric vector containing initial estimates for the nonlinear model parameters or a list with components

nlpars: the initial estimates of the nonlinear model parameters
theta: the initial estimates of the variance component parameters

Details

The model formula for a nonlinear mixed-effects model is of the form resp ~ nlmod ~ mixed where "resp" is an expression (usually just a name) for the response, nlmod is the call to the nonlinear model function, and mixed is the mixed-effects formula defining the linear predictor for the parameter matrix. If the formula is to be used for optimizing designs, the "resp" part can be omitted.

Value

a list with components