Product of the Hessian matrix of the Rosenbrock function with a vector.
x : array_like
1-D array of points at which the Hessian matrix is to be computed.
p : array_like
1-D array, the vector to be multiplied by the Hessian matrix.
rosen_hess_prod : ndarray
The Hessian matrix of the Rosenbrock function at x multiplied by the vector p.