function fun=exc7eqc(t,u,ud)
   fun=[ud(1)-u(2);
        -u(2)*ud(4)*sin(u(1)*u(3))-5*ud(2)*u(4)*cos(u(1)^2)-t*u(1)*u(3)^2+exp(-u(3)^2);
        ud(3)-u(4);
        -ud(2)*u(3)-ud(4)*u(2)*sin(u(1)^2)-cos(ud(4)*u(3))-sin(t)];