// Code generated by stanc v2.31.0
#include <stan/model/model_header.hpp>
namespace minimalODEExampleExternal_model_namespace {

struct odefunc_functor__ {
  template <typename T0__, typename T1__, typename T2__,
            stan::require_all_t<stan::is_stan_scalar<T0__>,
                                stan::is_col_vector<T1__>,
                                stan::is_vt_not_complex<T1__>,
                                stan::is_stan_scalar<T2__>>* = nullptr>
  Eigen::Matrix<stan::promote_args_t<T0__, stan::base_type_t<T1__>, T2__>, -1, 1>
  operator()(const T0__& t, const T1__& y, const T2__& theta,
             std::ostream* pstream__) const;
};

template <typename T1__,
          stan::require_all_t<stan::is_col_vector<T1__>,
                              stan::is_vt_not_complex<T1__>>* = nullptr>
Eigen::Matrix<stan::math::var, -1, 1>
odefunc(
  const double& t,
  const T1__& y,
  const double& theta,
  std::ostream* pstream__
) {

  Eigen::Matrix<stan::math::var, -1, 1> dydt = Eigen::Matrix<stan::math::var, -1, 1>::Constant(2, 0.0);
  dydt[0] = y[1].val();
  dydt[1] = -theta * y[0].val();

  Eigen::Matrix<double, -1, -1> jacobian = Eigen::Matrix<double, -1, -1>::Constant(2, 2, 0.0);
  jacobian(0,1) = 1.0;
  jacobian(1,0) = -theta;

  stan::arena_t<T1__> y_arena = y;
  stan::math::make_callback_var(dydt, [y_arena, jacobian](auto& res){
    y_arena.adj() += jacobian.transpose() * res.adj();
  });
  return dydt;
}

Eigen::Matrix<double, -1, 1>
odefunc(
  const double& t,
  const Eigen::Matrix<double,-1,1>& y,
  const double& theta,
  std::ostream* pstream__
) {

  Eigen::Matrix<double, -1, 1> dydt = Eigen::Matrix<double, -1, 1>::Constant(2, 0.0);
  dydt[0] = y[1];
  dydt[1] = -theta * y[0];

  return dydt;
}


template <typename T0__, typename T1__, typename T2__,
          stan::require_all_t<stan::is_stan_scalar<T0__>,
                              stan::is_col_vector<T1__>,
                              stan::is_vt_not_complex<T1__>,
                              stan::is_stan_scalar<T2__>>*>
Eigen::Matrix<stan::promote_args_t<T0__, stan::base_type_t<T1__>, T2__>, -1, 1>
odefunc_functor__::operator()(const T0__& t, const T1__& y,
                              const T2__& theta, std::ostream* pstream__) const
{
  return odefunc(t, y, theta, pstream__);
}


} //namespace