boost::geometry::distance performance overhead compared to a straightforward implementation, C++ (clang)

boost::geometry::distance performance overhead compared to a straightforward implementation

#include <iostream>
#include <iomanip>
#include <ctime>
#include <boost/geometry.hpp>
#include <boost/geometry/geometries/point_xy.hpp>

using namespace boost::geometry;
using namespace std;

const int N = 3000;

struct Point {
  float x, y;
  float distance(const Point& p) const {return sqrt((x-p.x)*(x-p.x)+(y-p.y)*(y-p.y));}
};

array<model::d2::point_xy<float>, N> a0;
array<Point, N>                      a1;

float f0() {
  float d = 0;

for (auto p: a0)
    for (auto q: a0)
      d += boost::geometry::distance(p, q);

return d;
}

float f1() {
  float d = 0;

for (auto p: a1)
    for (auto q: a1)
      d += p.distance(q);

return d;
}

int main()
{
  for (int i = 0; i < N; ++i) {
    a0[i] = {(float)i, (float)i};
    a1[i] = {(float)i, (float)i};
  }

auto benchmark = [](float (*f)()) {
    const int      N = 10;
    float          result = 0;
    vector<double> timings(N);

for (int i = 0; i < N; ++i) {
      volatile auto t0 = clock();
      volatile auto r  = f();
      volatile auto t1 = clock();

result    += r;
      timings[i] = (double)(t1-t0)/CLOCKS_PER_SEC;
    }
    
    sort(timings.begin(), timings.end());
    cout << fixed << setprecision(6);
    cout << timings.front() << "s  <ctime> min\n";
    cout << timings[timings.size()/2] << "s  <ctime> median\n";
    cout << "Result: " << result << "\n\n";

return timings.front();
  };

double overhead = benchmark(f0)/benchmark(f1);

cout << "Boost.geometry overhead: " << setprecision(2) << overhead << "\n";

return 0;
}


run \| edit \| history \| help	0

λ

                                      .NET NoSQL database for rapid development