function [val,grad,Hess] = rosenbrockFN(x)
val = 100*(x(2)- x(1).^2).^2 + (1 - x(1)).^2;
grad = [-400*(x(2)- x(1).^2).*x(1) - 2*(1 - x(1));200*(x(2)- x(1).^2)];
Hess = [1200*x(1)^2 - 400*x(2)+ 2,-400*x(1);-400*x(1), 200];