R: Specify a Constant in a "nonlin" Function Predictor

Const {gnm} | R Documentation

## Specify a Constant in a "nonlin" Function Predictor

### Description

A symbolic wrapper to specify a constant in the predictor of a `"nonlin"` function.

### Usage

    Const(const)

### Arguments

`const` | a numeric value.

### Value

A call to `rep` used to create a variable representing the constant in the model frame.

### Note

`Const` may only be used in the predictor of a `"nonlin"` function. Use `offset` to specify a constant in the model formula.

### Author(s)

Heather Turner

### See Also

`gnm`, `formula`, `offset`

### Examples

    ## One way to fit the logistic function without conditional
    ## linearity as in ?nls
    library(gnm)
    set.seed(1)
    DNase1 <- subset(DNase, Run == 1)

    test <- gnm(density ~ -1 +
                Mult(1, Inv(Const(1) + Exp(Mult(1 + offset(-log(conc)),
                                                    Inv(1))))),
                start = c(NA, 0, 1), data = DNase1, trace = TRUE)
    coef(test)

[Package gnm version 1.0-8 Index]