Explicit typing

Author: andrjohns

stan/math/fwd/fun/hypergeometric_1F0.hpp

@@ -25,12 +25,13 @@ namespace math {
  * @param[in] z Scalar z argument
  * @return Hypergeometric 1F0 function
  */
-template <typename Ta, typename Tz, require_any_fvar_t<Ta, Tz>* = nullptr>
-auto hypergeometric_1f0(const Ta& a, const Tz& z) {
-  using FvarT = return_type_t<Ta, Tz>;
-
-  auto a_val = value_of(a);
-  auto z_val = value_of(z);
+template <typename Ta, typename Tz,
+          typename FvarT = return_type_t<Ta, Tz>,
+          require_all_stan_scalar_t<Ta, Tz>* = nullptr,
+          require_any_fvar_t<Ta, Tz>* = nullptr>
+FvarT hypergeometric_1f0(const Ta& a, const Tz& z) {
+  partials_type_t<Ta> a_val = value_of(a);
+  partials_type_t<Tz> z_val = value_of(z);
   FvarT rtn = FvarT(hypergeometric_1f0(a_val, z_val), 0.0);
   if (!is_constant_all<Ta>::value) {
     rtn.d_ += forward_as<FvarT>(a).d() * -rtn.val() * log1m(z_val);

stan/math/prim/fun/hypergeometric_1F0.hpp

@@ -27,10 +27,11 @@ namespace math {
  * @param[in] z Scalar z argument
  * @return Hypergeometric 1F0 function
  */
-template <typename Ta, typename Tz, require_all_arithmetic_t<Ta, Tz>* = nullptr>
-auto hypergeometric_1f0(const Ta& a, const Tz& z) {
+template <typename Ta, typename Tz,
+          require_all_arithmetic_t<Ta, Tz>* = nullptr>
+double hypergeometric_1f0(const Ta& a, const Tz& z) {
   constexpr const char* function = "hypergeometric_1f0";
-  check_less("hypergeometric_1f0", "abs(z)", std::abs(z), 1.0);
+  check_less("hypergeometric_1f0", "abs(z)", std::fabs(z), 1.0);
 
   return boost::math::hypergeometric_1F0(a, z, boost_policy_t<>());
 }

stan/math/rev/fun/hypergeometric_1F0.hpp

@@ -28,7 +28,9 @@ namespace math {
  * @param[in] z Scalar z argument
  * @return Hypergeometric 1F0 function
  */
-template <typename Ta, typename Tz, require_any_var_t<Ta, Tz>* = nullptr>
+template <typename Ta, typename Tz,
+          require_all_stan_scalar_t<Ta, Tz>* = nullptr,
+          require_any_var_t<Ta, Tz>* = nullptr>
 var hypergeometric_1f0(const Ta& a, const Tz& z) {
   double a_val = value_of(a);
   double z_val = value_of(z);