function  z=d3fnv3p5(t,y);
%% 3rd derivative with respect to t of the function f(t,y(t)) found in
%% Burden and Faires Chap 5 Sect 3 problem 5
z=-12*(t.^(-4)).*y +12*(t.^(-3)).*fnv3p5(t,y)-6*(t.^(-2)).*dfnv3p5(t,y)+..
2*(t.^(-1)).*d2fnv3p5(t,y)+(t.^2+6*t+6).*exp(t);
