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- //---------------------------------------------------------------------------//
- // Copyright (c) 2013 Kyle Lutz <kyle.r.lutz@gmail.com>
- //
- // Distributed under 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
- //
- // See http://boostorg.github.com/compute for more information.
- //---------------------------------------------------------------------------//
- #include <iostream>
- #include <boost/compute/function.hpp>
- #include <boost/compute/system.hpp>
- #include <boost/compute/algorithm/count_if.hpp>
- #include <boost/compute/container/vector.hpp>
- #include <boost/compute/iterator/buffer_iterator.hpp>
- #include <boost/compute/random/default_random_engine.hpp>
- #include <boost/compute/types/fundamental.hpp>
- namespace compute = boost::compute;
- int main()
- {
- // get default device and setup context
- compute::device gpu = compute::system::default_device();
- compute::context context(gpu);
- compute::command_queue queue(context, gpu);
- std::cout << "device: " << gpu.name() << std::endl;
- using compute::uint_;
- using compute::uint2_;
- #ifdef CI_BUILD // lower number of points for CI builds
- size_t n = 2000;
- #else
- // ten million random points
- size_t n = 10000000;
- #endif
- // generate random numbers
- compute::default_random_engine rng(queue);
- compute::vector<uint_> vector(n * 2, context);
- rng.generate(vector.begin(), vector.end(), queue);
- // function returing true if the point is within the unit circle
- BOOST_COMPUTE_FUNCTION(bool, is_in_unit_circle, (const uint2_ point),
- {
- const float x = point.x / (float) UINT_MAX - 1;
- const float y = point.y / (float) UINT_MAX - 1;
- return (x*x + y*y) < 1.0f;
- });
- // iterate over vector<uint> as vector<uint2>
- compute::buffer_iterator<uint2_> start =
- compute::make_buffer_iterator<uint2_>(vector.get_buffer(), 0);
- compute::buffer_iterator<uint2_> end =
- compute::make_buffer_iterator<uint2_>(vector.get_buffer(), vector.size() / 2);
- // count number of random points within the unit circle
- size_t count = compute::count_if(start, end, is_in_unit_circle, queue);
- // print out values
- float count_f = static_cast<float>(count);
- std::cout << "count: " << count << " / " << n << std::endl;
- std::cout << "ratio: " << count_f / float(n) << std::endl;
- std::cout << "pi = " << (count_f / float(n)) * 4.0f << std::endl;
- return 0;
- }
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