//  (C) Copyright John Maddock 2006.
//  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)

#include <boost/math/concepts/real_concept.hpp>
#include <boost/test/included/test_exec_monitor.hpp>
#include <boost/test/floating_point_comparison.hpp>
#include <boost/math/special_functions/factorials.hpp>
#include <boost/math/special_functions/gamma.hpp>
#include <boost/math/tools/stats.hpp>
#include <boost/math/tools/test.hpp>

template <class T>
void test_spots(T)
{
   //
   // basic sanity checks, tolerance is 10 decimal places expressed as a percentage,
   // One check per domain of the implementation:
   //
   T tolerance = boost::math::tools::epsilon<T>() * 100 * 2;  // 2 eps as a persent
   BOOST_CHECK_CLOSE(
      ::boost::math::factorial<T>(0),
      static_cast<T>(1), tolerance);
   BOOST_CHECK_CLOSE(
      ::boost::math::factorial<T>(1),
      static_cast<T>(1), tolerance);
   BOOST_CHECK_CLOSE(
      ::boost::math::factorial<T>(10),
      static_cast<T>(3628800L), tolerance);
   BOOST_CHECK_CLOSE(
      ::boost::math::unchecked_factorial<T>(0),
      static_cast<T>(1), tolerance);
   BOOST_CHECK_CLOSE(
      ::boost::math::unchecked_factorial<T>(1),
      static_cast<T>(1), tolerance);
   BOOST_CHECK_CLOSE(
      ::boost::math::unchecked_factorial<T>(10),
      static_cast<T>(3628800L), tolerance);

   tolerance = boost::math::tools::epsilon<T>() * 100 * 20;  // 20 eps as a persent
   unsigned i = boost::math::max_factorial<T>::value;
   BOOST_CHECK_CLOSE(
      ::boost::math::unchecked_factorial<T>(i),
      boost::math::tgamma(static_cast<T>(i+1)), tolerance);

   i += 10;
   while(boost::math::lgamma(static_cast<T>(i+1)) < boost::math::tools::log_max_value<T>())
   {
      BOOST_CHECK_CLOSE(
         ::boost::math::factorial<T>(i),
         boost::math::tgamma(static_cast<T>(i+1)), tolerance);
      i += 10;
   }

}

int test_main(int, char* [])
{
   test_spots(0.0F);
   test_spots(0.0);
   test_spots(0.0L);
   test_spots(boost::math::concepts::real_concept(0.1));
   return 0;
}