acosh.hpp

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#ifndef STAN_MATH_PRIM_FUN_ACOSH_HPP
#define STAN_MATH_PRIM_FUN_ACOSH_HPP
 
#include <stan/math/prim/meta.hpp>
#include <stan/math/prim/err.hpp>
#include <stan/math/prim/fun/copysign.hpp>
#include <stan/math/prim/fun/is_inf.hpp>
#include <stan/math/prim/fun/is_nan.hpp>
#include <stan/math/prim/fun/log.hpp>
#include <stan/math/prim/fun/sqrt.hpp>
#include <stan/math/prim/functor/apply_scalar_unary.hpp>
#include <cmath>
#include <complex>
 
namespace stan {
namespace math {
 
template <typename T, require_arithmetic_t<T>* = nullptr>
inline double acosh(T&& x) {
  if (is_nan(x)) {
    return x;
  } else {
    check_greater_or_equal("acosh", "x", x, 1.0);
#ifdef _WIN32
    if (is_inf(x))
      return x;
#endif
    return std::acosh(x);
  }
}
 
template <typename T, require_complex_bt<std::is_arithmetic, T>* = nullptr>
inline auto acosh(T&& x) {
  return std::acosh(x);
}
 
struct acosh_fun {
  template <typename T>
  static inline auto fun(T&& x) {
    return acosh(std::forward<T>(x));
  }
};
 
template <typename T, require_ad_container_t<T>* = nullptr>
inline auto acosh(T&& x) {
  return apply_scalar_unary<acosh_fun, T>::apply(std::forward<T>(x));
}
 
template <typename Container,
          require_container_bt<std::is_arithmetic, Container>* = nullptr>
inline auto acosh(Container&& x) {
  return apply_scalar_unary<acosh_fun, Container>::apply(
      std::forward<Container>(x));
}
 
namespace internal {
 
template <typename V>
inline std::complex<V> complex_acosh(const std::complex<V>& z) {
  std::complex<double> y_d = acosh(value_of_rec(z));
  auto y = log(z + sqrt(z * z - 1));
  return copysign(y, y_d);
}
 
}  // namespace internal
 
}  // namespace math
}  // namespace stan
 
#endif