x(times, pars, forcings, events) returning ODE output.
It is a reduced version of Xs, missing the sensitivities.Xf(func, forcings = NULL, events = NULL, optionsOde = list(method =
"lsoda"))funC(f) where f defines the ODE.f. All quantities that are not initialised by pars
in x(times, pars, forcings, events) are initialized at 0.