//  (C) Copyright John Maddock 2005.

//  Use, modification and distribution are subject to the

//  Boost Software License, Version 1.0. (See accompanying file

//  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

#ifndef BOOST_MATH_COMPLEX_ACOSH_INCLUDED

#define BOOST_MATH_COMPLEX_ACOSH_INCLUDED

#ifndef BOOST_MATH_COMPLEX_DETAILS_INCLUDED

#  include <boost/math/complex/details.hpp>

#endif

#ifndef BOOST_MATH_COMPLEX_ATANH_INCLUDED

#  include <boost/math/complex/acos.hpp>

#endif

namespace boost{ namespace math{

template<class T> 

inline std::complex<T> acosh(const std::complex<T>& z)

{

   //

   // We use the relation acosh(z) = +-i acos(z)

   // Choosing the sign of multiplier to give real(acosh(z)) >= 0

   // as well as compatibility with C99.

   //

   std::complex<T> result = boost::math::acos(z);

   if(!detail::test_is_nan(result.imag()) && result.imag() <= 0)

      return detail::mult_i(result);

   return detail::mult_minus_i(result);

}

} } // namespaces

#endif // BOOST_MATH_COMPLEX_ACOSH_INCLUDED