Three-parameter shifted asymptotic regression model

A three-parameter asymptotic regression model where b is fixed at 1. The model is given by the equation $$f(x) = c + (d - c)(1 - \exp(-x / e))$$

Usage

AR.3(fixed = c(NA, NA, NA), names = c("c", "d", "e"), ...)

fixed: numeric vector of length 3, specifying fixed parameters (use NA for parameters that should be estimated).
names: character vector of length 3 giving the names of the parameters (default c("c", "d", "e")).
...: additional arguments passed to weibull2, most notably method (a character string: "1" (default), "2", "3", or "4") which selects the self-starter method for obtaining starting values. See weibull2 for details.

A list of class "Weibull-2" as returned by weibull2.

ryegrass.m1 <- drm(rootl ~ conc, data = ryegrass, fct = AR.3())