1 //  (C) Copyright John Maddock 2005.

     2 //  Use, modification and distribution are subject to the

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

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

     5 

     6 #ifndef BOOST_MATH_COMPLEX_ATAN_INCLUDED

     7 #define BOOST_MATH_COMPLEX_ATAN_INCLUDED

     8 

     9 #ifndef BOOST_MATH_COMPLEX_DETAILS_INCLUDED

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

    11 #endif

    12 #ifndef BOOST_MATH_COMPLEX_ATANH_INCLUDED

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

    14 #endif

    15 

    16 namespace boost{ namespace math{

    17 

    18 template<class T> 

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

    20 {

    21    //

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

    23    //

    24    if(x.real() == 0)

    25    {

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

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

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

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

    30    }

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

    32 }

    33 

    34 } } // namespaces

    35 

    36 #endif // BOOST_MATH_COMPLEX_ATAN_INCLUDED