text: //  (C) Copyright Simon West 2011.
  //  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/test/unit_test.hpp>
  #include <boost/accumulators/accumulators.hpp>
  #include <boost/accumulators/statistics/stats.hpp>
  #include <boost/accumulators/statistics/weighted_sum_kahan.hpp>
  #include <boost/accumulators/statistics/variates/covariate.hpp>
  
  using namespace boost;
  using namespace unit_test;
  using namespace accumulators;
  
  ///////////////////////////////////////////////////////////////////////////////
  // test_weighted_sum_kahan
  //
  void test_weighted_sum_kahan()
  {
      accumulator_set<float, stats<tag::weighted_sum_kahan>, float > acc;
  
      BOOST_CHECK_EQUAL(0.0f, weighted_sum_kahan(acc));
  
      for (size_t i = 0; i < 1e6; ++i) {
          acc(1, weight = 1e-6f);
      }
  
      BOOST_CHECK_EQUAL(1.0f, weighted_sum_kahan(acc));
  }
  
  ///////////////////////////////////////////////////////////////////////////////
  // test_weighted_sum_of_variates_kahan
  //
  void test_weighted_sum_of_variates_kahan()
  {
      accumulator_set<
          float, 
          stats<tag::weighted_sum_of_variates_kahan<float, tag::covariate1> >,
          float
      >
      acc;
  
      BOOST_CHECK_EQUAL(0.0f, weighted_sum_of_variates_kahan(acc));
  
      for (size_t i = 0; i < 1e6; ++i) {
        acc(0, weight = 1.0f, covariate1 = 1e-6f);
      }
  
      BOOST_CHECK_EQUAL(1.0f, weighted_sum_of_variates_kahan(acc));
  }
  
  ///////////////////////////////////////////////////////////////////////////////
  // init_unit_test_suite
  //
  test_suite* init_unit_test_suite( int argc, char* argv[] )
  {
      test_suite *test = BOOST_TEST_SUITE("weighted sum kahan tests");
  
      test->add(BOOST_TEST_CASE(&test_weighted_sum_kahan));
      test->add(BOOST_TEST_CASE(&test_weighted_sum_of_variates_kahan));
  
      return test;
  }
  