gompertz_fn: Gompertz function

In drda: Dose-Response Data Analysis

Gompertz function

Description

Evaluate at a particular set of parameters the Gompertz function.

Usage

gompertz_fn(x, theta)

Arguments

x	numeric vector at which the Gompertz function is to be evaluated.
theta	numeric vector with the four parameters in the form c(alpha, delta, eta, phi).

Details

The Gompertz function ⁠f(x; theta)⁠ is defined here as

⁠g(x; theta) = exp(-exp(-eta * (x - phi)))⁠ ⁠f(x; theta) = alpha + delta g(x; theta)⁠

where theta = c(alpha, delta, eta, phi), alpha is the value of the function when x -> -Inf, delta is the (signed) height of the curve, eta > 0 is the steepness of the curve or growth rate, and phi is related with the value of function at x = 0.

When delta < 0 the curve is monotonically decreasing while it is monotonically increasing for delta > 0.

Value

Numeric vector of the same length of x with the values of the Gompertz function.

drda documentation built on April 3, 2025, 6 p.m.