x(times, pars, forcings, events) returning ODE output.
It is a reduced version of Xs, missing the sensitivities.
Xf(odemodel, forcings = NULL, events = NULL, condition = NULL, optionsOde = list(method = "lsoda"))f. 
All quantities that are not initialised by pars 
in x(..., forcings, events) are initialized with 0. For more details and
the return value see Xs.