multiprecision/test/test_cpp_dec_float_tgamma.cpp

///////////////////////////////////////////////////////////////
//  Copyright Christopher Kormanyos 2021.
//  Copyright 2021 John Maddock. Distributed under the Boost
//  Software License, Version 1.0. (See accompanying file
//  LICENSE_1_0.txt or copy at https://www.boost.org/LICENSE_1_0.txt
//

#include <boost/detail/lightweight_test.hpp>
#include <boost/math/special_functions/gamma.hpp>
#include "test.hpp"

#include <boost/multiprecision/cpp_dec_float.hpp>

namespace local
{
  template<typename T> constexpr T (max)(T a, T b) { return a > b ? a : b; }

  template<class T>
  void test()
  {
     // N[Gamma[5/2], 120]
     const T control_tgamma_2_and_half("1.32934038817913702047362561250585888709816209209179034616035584238968346344327413603121299255390849906217011771821192800");

     // N[Gamma[500/2], 120]
     const T control_tgamma_2_fifty   ("1.29314250436364309292832582080974738839793748706951226669917697084512949902204448379552716614841127978037140294127577317E490");

     const T tgamma_2_and_half = boost::math::tgamma(T(T(5)   / 2));
     const T tgamma_2_fifty    = boost::math::tgamma(T(T(500) / 2));

     BOOST_CHECK_CLOSE_FRACTION(tgamma_2_and_half, control_tgamma_2_and_half, T(std::numeric_limits<T>::epsilon() * T(1.0E6)));
     BOOST_CHECK_CLOSE_FRACTION(tgamma_2_fifty   , control_tgamma_2_fifty,    T(std::numeric_limits<T>::epsilon() * T(1.0E6)));
  }
}

int main()
{
   using big_float_type_016 = boost::multiprecision::number<boost::multiprecision::cpp_dec_float<(local::max)((int) (std::numeric_limits<double>::digits + 1), 16)>>;
   using big_float_type_035 = boost::multiprecision::number<boost::multiprecision::cpp_dec_float<(local::max)((int) (std::numeric_limits<double>::digits + 1), 35)>>;
   using big_float_type_105 = boost::multiprecision::number<boost::multiprecision::cpp_dec_float<105>>;

   local::test<big_float_type_016>();
   local::test<big_float_type_035>();
   local::test<big_float_type_105>();

   return boost::report_errors();
}