gompertzd {drc}R Documentation

The derivative of the Gompertz function

Description

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

Usage

  gompertzd(lowerc = c(-Inf, -Inf), upperc = c(Inf, Inf),
  fixed = c(NA, NA), names = c("a", "b"))

Arguments

lowerc numeric vector. The lower bound on parameters. Default is minus infinity.
upperc numeric vector. The upper bound on parameters. Default is plus infinity.
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 non-linear function, the self starter function and the parameter names.

Note

This function is for use with the function drm.

Author(s)

Christian Ritz


[Package drc version 1.6-1 Index]