What’s the function signature need to look like for the first argument of stan::math::hessian?
I have a signature like:
template <typename T_x>
inline const return_type_t<T_x>
f2(const std::vector<T_x> &x)
and the compiler doesn’t like the first argument, gives: <unresolved overloaded function type>
.
How should I define const F &
, the first argument for stan::math::hessian?
Thanks!