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// (C) Copyright John Maddock 2013.
// 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/special_functions/bernoulli.hpp>
#include <boost/chrono.hpp>
#include <boost/multiprecision/cpp_dec_float.hpp>
template <class Clock>
struct stopwatch
{
typedef typename Clock::duration duration;
stopwatch()
{
m_start = Clock::now();
}
duration elapsed()
{
return Clock::now() - m_start;
}
void reset()
{
m_start = Clock::now();
}
private:
typename Clock::time_point m_start;
};
void time()
{
stopwatch<boost::chrono::high_resolution_clock> w;
//
// Sum the first 1000 Bernoulli numbers:
//
boost::multiprecision::cpp_dec_float_50 sum = 0;
for(unsigned i = 0; i < 1000; ++i)
{
sum += boost::math::bernoulli_b2n<boost::multiprecision::cpp_dec_float_50>(i);
}
double t = boost::chrono::duration_cast<boost::chrono::duration<double> >(w.elapsed()).count();
std::cout << "Total execution time = " << std::setprecision(3) << t << "s" << std::endl;
std::cout << "Sum was: " << sum << std::endl;
}
int main()
{
// Call time() twice: first call results in the cache being populated, second used already cached values:
time();
time();
return 0;
}
/*
No atomic int:
Total execution time = 0.646s
Sum was: 2.86e+4134
Total execution time = 0.000341s
Sum was: 2.86e+4134
With atomic int:
Total execution time = 0.643s
Sum was: 2.86e+4134
Total execution time = 0.000309s
Sum was: 2.86e+4134
No threads:
Total execution time = 0.652s
Sum was: 2.86e+4134
Total execution time = 0.000281s
Sum was: 2.86e+4134
*/
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