The derivative (i.e. gradient) of the Rosenbrock function.
x : array_like
1-D array of points at which the derivative is to be computed.
rosen_der : (N,) ndarray
The gradient of the Rosenbrock function at x.
See also
rosen, rosen_hess, rosen_hess_prod
scipy.optimize.rosen
scipy.optimize.rosen_hess