nlformula {lme4} R Documentation

## Manipulate a Nonlinear Model Formula

### Description

Check and manipulate the formula for a nonlinear model, such as specified in nlmer.

### Usage

  nlformula(mc)


### Arguments

 mc matched call from the calling function, typically nlmer(). 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

 "respMod" a response module of class "nlsResp" "frame" the model frame, including a terms attribute "X" the fixed-effects model matrix "reTrms" the random-effects terms object

Other utilities: findbars, mkRespMod, mkReTrms, nobars, subbars