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80 lines
1.7 KiB
C++
80 lines
1.7 KiB
C++
// (C) Copyright John Maddock 2013.
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// Use, modification and distribution are subject to the
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// Boost Software License, Version 1.0. (See accompanying file
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// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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#include <boost/math/special_functions/bernoulli.hpp>
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#include <boost/chrono.hpp>
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#include <boost/multiprecision/cpp_dec_float.hpp>
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template <class Clock>
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struct stopwatch
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{
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typedef typename Clock::duration duration;
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stopwatch()
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{
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m_start = Clock::now();
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}
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duration elapsed()
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{
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return Clock::now() - m_start;
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}
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void reset()
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{
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m_start = Clock::now();
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}
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private:
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typename Clock::time_point m_start;
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};
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void time()
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{
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stopwatch<boost::chrono::high_resolution_clock> w;
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//
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// Sum the first 1000 Bernoulli numbers:
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//
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boost::multiprecision::cpp_dec_float_50 sum = 0;
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for(unsigned i = 0; i < 1000; ++i)
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{
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sum += boost::math::bernoulli_b2n<boost::multiprecision::cpp_dec_float_50>(i);
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}
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double t = boost::chrono::duration_cast<boost::chrono::duration<double> >(w.elapsed()).count();
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std::cout << "Total execution time = " << std::setprecision(3) << t << "s" << std::endl;
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std::cout << "Sum was: " << sum << std::endl;
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}
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int main()
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{
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// Call time() twice: first call results in the cache being populated, second used already cached values:
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time();
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time();
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return 0;
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}
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/*
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No atomic int:
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Total execution time = 0.646s
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Sum was: 2.86e+4134
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Total execution time = 0.000341s
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Sum was: 2.86e+4134
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With atomic int:
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Total execution time = 0.643s
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Sum was: 2.86e+4134
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Total execution time = 0.000309s
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Sum was: 2.86e+4134
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No threads:
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Total execution time = 0.652s
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Sum was: 2.86e+4134
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Total execution time = 0.000281s
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Sum was: 2.86e+4134
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*/
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