logistic2_fn {drda} | R Documentation |
Evaluate at a particular set of parameters the 2-parameter logistic function.
logistic2_fn(x, theta)
x |
numeric vector at which the logistic function is to be evaluated. |
theta |
numeric vector with the parameters in the form |
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.
Numeric vector of the same length of x
with the values of the
logistic function.