gompertzd: The derivative of the Gompertz function

In drc: Analysis of Dose-Response Curves

Description

'gompertzd' provides a way of specifying the derivative of the Gompertz function as a dose-response model.

Usage

  gompertzd(fixed = c(NA, NA), names = c("a", "b"))

Arguments

fixed	numeric vector. Specifies which parameters are fixed and at what value they are fixed. NAs for parameter that are not fixed.
names	a vector of character strings giving the names of the parameters (should not contain ":"). The default is (notice the order): a, b.

Details

The derivative of the Gompertz function is defined as

f(x) = a \exp(bx-a/b(exp(bx)-1))

For a>0 and b not 0, the function is decreasing, equaling a at x=0 and approaching 0 at plus infinity.

Value

The value returned is a list containing the model function, the self starter function and the parameter names.

Note

This function is for use with the function drm.

Author(s)

Christian Ritz

drc documentation built on May 1, 2019, 8:43 p.m.