function H = Hessiano_exa(x)
n = length(x);
H = zeros(n, n);

H(1,1) = 2+800*x(1)^2 - 400*(-x(1)^2 + x(2));
H(1,2) = -400*x(1);
H(2,1) = -400*x(1);
H(2,2) = 200;