//  (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_ATAN_INCLUDED

 #define BOOST_MATH_COMPLEX_ATAN_INCLUDED

 #ifndef BOOST_MATH_COMPLEX_DETAILS_INCLUDED

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

 #endif

 #ifndef BOOST_MATH_COMPLEX_ATANH_INCLUDED

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

 #endif

 namespace boost{ namespace math{

 template<class T> 

 std::complex<T> atan(const std::complex<T>& x)

 {

    //

    // We're using the C99 definition here; atan(z) = -i atanh(iz):

    //

    if(x.real() == 0)

    {

       if(x.imag() == 1)

          return std::complex<T>(0, std::numeric_limits<T>::has_infinity ? std::numeric_limits<T>::infinity() : static_cast<T>(HUGE_VAL));

       if(x.imag() == -1)

          return std::complex<T>(0, std::numeric_limits<T>::has_infinity ? -std::numeric_limits<T>::infinity() : -static_cast<T>(HUGE_VAL));

    }

    return ::boost::math::detail::mult_minus_i(::boost::math::atanh(::boost::math::detail::mult_i(x)));

 }

 } } // namespaces

 #endif // BOOST_MATH_COMPLEX_ATAN_INCLUDED