wd=derv3b(t,w);

function wd=derv3b(t,w);
% example of linear differential equation
% in the form required by ODE23 and ODE45.

[m,n]=size(w);
wd = zeros(m,n);
wd(1)=w(2);
wd(2)=w(3);
wd(3)= cos(t) ...
       +5*cos(2*t)/(t+1)^2*w(3)    ...
       -w(2)                       ...
       - w(1)/(3+sin(t));