logistic2_fn {drda}R Documentation

2-parameter logistic function

Description

Evaluate at a particular set of parameters the 2-parameter logistic function.

Usage

logistic2_fn(x, theta)

Arguments

x

numeric vector at which the logistic function is to be evaluated.

theta

numeric vector with the parameters in the form c(eta, phi).

Details

The 2-parameter logistic function ⁠f(x; theta)⁠ is defined here as

1 / (1 + exp(-eta * (x - phi)))

where theta = c(eta, phi), eta is the steepness of the curve or growth rate (also known as the Hill coefficient), and phi is the value of x at which the curve is equal to its mid-point, i.e. 1 / 2.

Value

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


[Package drda version 1.0.0 Index]