R: The derivative of the Gompertz function

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(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

[Package drc version 3.0-1 Index]