std::function<void(const state_type, state_type, const double)> eqsir2(const Rcpp::NumericVector theta) {
  return [&theta](const state_type &x, state_type &dxdt, const double t) {
    boost_array_to_nvec2(x, nvec);
    my_fun22(nvec,t,theta);
    nvec_to_boost_array2(nvec, dxdt);
  }