Analytical Gradient of the Inverse 4PL

Returns \(\partial x / \partial \theta\) and \(\partial x / \partial y\).

Usage

grad_logistic4(y, a, b, c, d)

Arguments

y

Numeric scalar. Observed response.

a, b, c, d

Numeric scalars. Free model parameters.

Value

List with grad_theta (named vector) and scalar grad_y.

See also

Other gradient-functions: grad_gompertz4(), grad_logistic5(), grad_loglogistic4(), grad_loglogistic5()