1 #ifndef STAN_MATH_PRIM_FUN_EXP2_HPP
2 #define STAN_MATH_PRIM_FUN_EXP2_HPP
3 
4 #include <stan/math/prim/meta.hpp>
5 #include <stan/math/prim/functor/apply_scalar_unary.hpp>
6 #include <cmath>
7 
8 namespace stan {
9 namespace math {
10 
11 /**
12  * Structure to wrap `exp2()` so it can be vectorized.
13  */
14 struct exp2_fun {
15   /**
16    * Return the base two exponent of the specified argument.
17    *
18    * @tparam T type of argument
19    * @param x argument
20    * @return Base two exponent of the argument.
21    */
22   template <typename T>
funstan::math::exp2_fun23   static inline T fun(const T& x) {
24     using std::exp2;
25     return exp2(x);
26   }
27 };
28 
29 /**
30  * Return the elementwise `exp2()` of the specified argument,
31  * which may be a scalar or any Stan container of numeric scalars.
32  * The return type is the same as the argument type.
33  *
34  * @tparam T type of container
35  * @param x container
36  * @return Elementwise exp2 of members of container.
37  */
38 template <
39     typename T,
40     require_all_not_nonscalar_prim_or_rev_kernel_expression_t<T>* = nullptr,
41     require_not_var_matrix_t<T>* = nullptr>
exp2(const T & x)42 inline auto exp2(const T& x) {
43   return apply_scalar_unary<exp2_fun, T>::apply(x);
44 }
45 
46 }  // namespace math
47 }  // namespace stan
48 
49 #endif
50