'gompertzd' provides a way of specifying the derivative of the Gompertz function as a dose-response model.
gompertzd(fixed = c(NA, NA), names = c("a", "b"))The value returned is a list containing the model function, the self starter function and the parameter names.
numeric vector. Specifies which parameters are fixed and at what value they are fixed. NAs for parameter that are not fixed.
a vector of character strings giving the names of the parameters (should not contain ":"). The default is (notice the order): a, b.
Christian Ritz
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.