Three-parameter exponential decay model

A three-parameter exponential decay model with the slope parameter b fixed at 1.

Usage

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

fixed: numeric vector of length 3. Specifies which parameters are fixed and at what value. Use NA for parameters that are not fixed.
names: character vector of length 3 giving the names of the parameters. The default is c("c", "d", "e").
...: additional arguments passed to weibull1, most notably method (a character string: "1" (default), "2", "3", or "4") which selects the self-starter method for obtaining starting values. See weibull1 for details.

A list of class Weibull-1 containing the nonlinear function, self starter function, and parameter names.

The model is given by the expression $$f(x) = c + (d - c) \exp(-x/e)$$

This is a special case of the Weibull type 1 model (weibull1) with the slope fixed at 1.

Seber, G. A. F. and Wild, C. J. (1989) Nonlinear Regression, New York: Wiley & Sons (pp. 338–339).

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