function examenRK() 
    h = 0.001;
    t = 0;
    
    r(1) = 0; 
    r(2) = 0;

    k1 = funcion(t, r)
    k2 = funcion(t+h/2, r+k1*h/2)
    k3 = funcion(t+h/2, r+k2*h/2)
    k4 = funcion(t+h, r+k3*h)
    
    r = r + (k1+2*k2+2*k3+k4)*h/6


    function di = funcion(t, r)
        x = r(1);
        y = r(2);
        di(1) = y;
        di(2) = 4 -y + 2*x;
    end
end