How to use RBF training to simulate this function, (simulation and using code seperatly)

f = @(x)(prod([x(1),x(2),x(3),x(5),x(3)-1])+x(4)) ./ (1 + x(2)^2 + x(3)^3);

k = 5; % demo value y = 1:5; % demo value u = 1:5; % demo value

y(k+1) = f([y(k), y(k-1), y(k-2), u(k), u(k-1)])