norm2.hpp

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#ifndef STAN_MATH_FWD_FUN_NORM2_HPP
#define STAN_MATH_FWD_FUN_NORM2_HPP
 
#include <stan/math/fwd/meta.hpp>
#include <stan/math/fwd/core.hpp>
#include <stan/math/prim/meta.hpp>
#include <stan/math/prim/fun/Eigen.hpp>
#include <stan/math/prim/fun/norm2.hpp>
#include <stan/math/prim/fun/to_ref.hpp>
 
namespace stan {
namespace math {
 
template <typename Container, require_eigen_vt<is_fvar, Container>* = nullptr>
inline auto norm2(const Container& x) {
  return apply_vector_unary<ref_type_t<Container>>::reduce(
      to_ref(x), [&](const auto& v) {
        using T_fvar_inner = typename value_type_t<decltype(v)>::Scalar;
        T_fvar_inner res = norm2(v.val());
        return fvar<T_fvar_inner>(res,
                                  v.d().cwiseProduct((v.val() / res)).sum());
      });
}
 
}  // namespace math
}  // namespace stan
#endif