Const {gnm}

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)