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_ACOSH_INCLUDED
7 #define BOOST_MATH_COMPLEX_ACOSH_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/acos.hpp>
14 #endif
15 
16 namespace boost{ namespace math{
17 
18 template<class T>
acosh(const std::complex<T> & z)19 inline std::complex<T> acosh(const std::complex<T>& z)
20 {
21    //
22    // We use the relation acosh(z) = +-i acos(z)
23    // Choosing the sign of multiplier to give real(acosh(z)) >= 0
24    // as well as compatibility with C99.
25    //
26    std::complex<T> result = boost::math::acos(z);
27    if(!(boost::math::isnan)(result.imag()) && signbit(result.imag()))
28       return detail::mult_i(result);
29    return detail::mult_minus_i(result);
30 }
31 
32 } } // namespaces
33 
34 #endif // BOOST_MATH_COMPLEX_ACOSH_INCLUDED
35