sl@0: //  (C) Copyright John Maddock 2005.
sl@0: //  Use, modification and distribution are subject to the
sl@0: //  Boost Software License, Version 1.0. (See accompanying file
sl@0: //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
sl@0: 
sl@0: #ifndef BOOST_MATH_COMPLEX_ACOSH_INCLUDED
sl@0: #define BOOST_MATH_COMPLEX_ACOSH_INCLUDED
sl@0: 
sl@0: #ifndef BOOST_MATH_COMPLEX_DETAILS_INCLUDED
sl@0: #  include <boost/math/complex/details.hpp>
sl@0: #endif
sl@0: #ifndef BOOST_MATH_COMPLEX_ATANH_INCLUDED
sl@0: #  include <boost/math/complex/acos.hpp>
sl@0: #endif
sl@0: 
sl@0: namespace boost{ namespace math{
sl@0: 
sl@0: template<class T> 
sl@0: inline std::complex<T> acosh(const std::complex<T>& z)
sl@0: {
sl@0:    //
sl@0:    // We use the relation acosh(z) = +-i acos(z)
sl@0:    // Choosing the sign of multiplier to give real(acosh(z)) >= 0
sl@0:    // as well as compatibility with C99.
sl@0:    //
sl@0:    std::complex<T> result = boost::math::acos(z);
sl@0:    if(!detail::test_is_nan(result.imag()) && result.imag() <= 0)
sl@0:       return detail::mult_i(result);
sl@0:    return detail::mult_minus_i(result);
sl@0: }
sl@0: 
sl@0: } } // namespaces
sl@0: 
sl@0: #endif // BOOST_MATH_COMPLEX_ACOSH_INCLUDED