logistic5_gradient {drda}  R Documentation 
Evaluate at a particular set of parameters the gradient and Hessian of the 5parameter logistic function.
logistic5_gradient(x, theta)
logistic5_hessian(x, theta)
logistic5_gradient_hessian(x, theta)
x 
numeric vector at which the function is to be evaluated. 
theta 
numeric vector with the five parameters in the form

The 5parameter logistic function f(x; theta)
is defined here as
g(x; theta) = 1 / (1 + nu * exp(eta * (x  phi)))^(1 / nu)
f(x; theta) = alpha + delta g(x; theta)
where theta = c(alpha, delta, eta, phi, nu)
, eta > 0
, and nu > 0
. When
delta
is positive (negative) the curve is monotonically increasing
(decreasing).
Gradient or Hessian evaluated at the specified point.