atan.hpp

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#ifndef STAN_MATH_PRIM_FUN_ATAN_HPP
#define STAN_MATH_PRIM_FUN_ATAN_HPP
 
#include <stan/math/prim/core.hpp>
#include <stan/math/prim/meta.hpp>
#include <stan/math/prim/fun/atanh.hpp>
#include <stan/math/prim/fun/Eigen.hpp>
#include <stan/math/prim/fun/i_times.hpp>
#include <stan/math/prim/functor/apply_scalar_unary.hpp>
#include <stan/math/prim/functor/apply_vector_unary.hpp>
#include <cmath>
#include <complex>
 
namespace stan {
namespace math {
 
struct atan_fun {
  template <typename T>
  static inline auto fun(const T& x) {
    using std::atan;
    return atan(x);
  }
};
 
template <typename Container,
          require_not_container_st<std::is_arithmetic, Container>* = nullptr,
          require_not_var_matrix_t<Container>* = nullptr,
          require_all_not_nonscalar_prim_or_rev_kernel_expression_t<
              Container>* = nullptr>
inline auto atan(const Container& x) {
  return apply_scalar_unary<atan_fun, Container>::apply(x);
}
 
template <typename Container,
          require_container_st<std::is_arithmetic, Container>* = nullptr>
inline auto atan(const Container& x) {
  return apply_vector_unary<Container>::apply(
      x, [](const auto& v) { return v.array().atan(); });
}
 
namespace internal {
template <typename V>
inline std::complex<V> complex_atan(const std::complex<V>& z) {
  return neg_i_times(atanh(i_times(z)));
}
}  // namespace internal
 
}  // namespace math
}  // namespace stan
 
#endif