function upr = lor(t, u)

global AA BB RR

upr(1) = -AA * u(1) + AA * u(2);
upr(2) =  RR * u(1) - u(2) - u(1) * u(3);
upr(3) = -BB * u(3) + u(1) * u(2);
upr = upr';

