text: #ifndef STAN_MATH_FWD_FUN_BESSEL_SECOND_KIND_HPP
  #define STAN_MATH_FWD_FUN_BESSEL_SECOND_KIND_HPP
  
  #include <stan/math/fwd/meta.hpp>
  #include <stan/math/fwd/core.hpp>
  #include <stan/math/prim/fun/bessel_second_kind.hpp>
  
  namespace stan {
  namespace math {
  
  template <typename T>
  inline fvar<T> bessel_second_kind(int v, const fvar<T>& z) {
    T bessel_second_kind_z(bessel_second_kind(v, z.val_));
    return fvar<T>(bessel_second_kind_z,
                   v * z.d_ * bessel_second_kind_z / z.val_
                       - z.d_ * bessel_second_kind(v + 1, z.val_));
  }
  }  // namespace math
  }  // namespace stan
  #endif
  