Derivative of the g-and-k log(Q) function.
Qgk_log_deriv(z, A, B, g, k, c = 0.8)
The derivative of the g-and-k Q function at p.
A vector of normal quantiles.
Vector of A (location) parameters.
Vector of B (scale) parameters. Must be positive.
Vector of g parameters.
Vector of k parameters. Must be greater than -0.5.
Vector of c parameters. Often fixed at 0.8 which is the default.