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 performance measurements

Each table row shows performance measurements for this C++ g++ program with a particular command-line input value N.

 N  CPU secs Elapsed secs Memory KB Code B ≈ CPU Load
500,0000.200.20?1668  5% 0% 0% 95%
5,000,0001.941.944321668  1% 1% 2% 100%
50,000,00019.3419.354321668  1% 1% 1% 100%

Read the ↓ make, command line, and program output logs to see how this program was run.

Read n-body benchmark to see what this program should do.

 notes

gcc version 4.8.2 (Ubuntu 4.8.2-19ubuntu1)

 n-body C++ g++ #6 program source code

/*
 * The Computer Language Benchmarks Game
 * http://benchmarksgame.alioth.debian.org/
 *
 * contributed by Jeffrey Beu
 * modified by Danny Angelo Carminati Grein
 *  
 */

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

namespace 
{

template< typename ...  > struct tuple{};

template<typename H, typename... T>
struct tuple<H,T...>
{
  typedef H head;
  typedef tuple<T...> tail;
 
  head fst;
  tail snd;
 
  tuple(const head& a,const tail& b):fst(a),snd(b){}
  tuple() = delete;
};

tuple<> construct_tuple()
{ return tuple<>();  
}

template<class H, class...T> tuple<H,T...> construct_tuple(H h, T... a)
{
  tuple<H,T...> r(h,construct_tuple(a...));
  return r;
}

template<class OP> void FOREACH(OP,tuple<>){}
template<typename OP,class ...T> void FOREACH(OP& op,tuple<T...>& t)
{
  op(t.fst);
  FOREACH(op,t.snd);
}

template<class OP> void FOR(OP,tuple<>){}

template<typename OP, class ...T> void FOR(OP& op,tuple<T...>& t)
{
  op(t);
  FOR(op,t.snd);
}



struct body {
  double x, y, z;
  double vx, vy, vz;
  const double mass;
};

const double pi = 3.141592653589793;
const double solar_mass = 4 * pi * pi;
const double days_per_year = 365.24;
const double dt = 0.01;

const body sun = 
{
  0,0,0,
  0,0,0,
  solar_mass
};

const body jupiter =  
{
   4.84143144246472090e+00,
  -1.16032004402742839e+00,
  -1.03622044471123109e-01,
   1.66007664274403694e-03 * days_per_year,
   7.69901118419740425e-03 * days_per_year,
  -6.90460016972063023e-05 * days_per_year,
   9.54791938424326609e-04 * solar_mass
};

const body saturn = 
{        
   8.34336671824457987e+00,
   4.12479856412430479e+00,
  -4.03523417114321381e-01,
  -2.76742510726862411e-03 * days_per_year,
   4.99852801234917238e-03 * days_per_year,
   2.30417297573763929e-05 * days_per_year,
   2.85885980666130812e-04 * solar_mass
};

const body uranus =
{ 
   1.28943695621391310e+01,
  -1.51111514016986312e+01,
  -2.23307578892655734e-01,
   2.96460137564761618e-03 * days_per_year,
   2.37847173959480950e-03 * days_per_year,
  -2.96589568540237556e-05 * days_per_year,
   4.36624404335156298e-05 * solar_mass
};

const body neptune = 
{  
   1.53796971148509165e+01,
  -2.59193146099879641e+01,
   1.79258772950371181e-01,
   2.68067772490389322e-03 * days_per_year,
   1.62824170038242295e-03 * days_per_year,
  -9.51592254519715870e-05 * days_per_year,
   5.15138902046611451e-05 * solar_mass
};


struct
{ struct 
  { template<class T> struct foreach_block
    { T &t;
      template<class T2> void operator()(T2& b2)
      {
	auto& b = t.fst;
        double dx = b.x - b2.x;
        double dy = b.y - b2.y;
        double dz = b.z - b2.z;
        double distanced = dx * dx + dy * dy + dz * dz;
        double distance = sqrt(distanced);
        double mag = dt / (distanced * distance);
        b.vx -= dx * b2.mass * mag;
        b.vy -= dy * b2.mass * mag;
        b.vz -= dz * b2.mass * mag;
        b2.vx += dx * b.mass * mag;
        b2.vy += dy * b.mass * mag;
        b2.vz += dz * b.mass * mag; 
      }     
    };

    
    template<class T> void operator()(T& bodies)
    {
      foreach_block<decltype(bodies)> run = {bodies};
      FOREACH(run,bodies.snd);
    }
  }for_block;


  struct
  {
    template<class T> void operator()(T& body) 
    {
      body.x += dt * body.vx;
      body.y += dt * body.vy;
      body.z += dt * body.vz;
    }
  }foreach_block;
  
  template<class T> void operator()(T& bodies)
  {
    FOR(for_block,bodies);
    FOREACH(foreach_block,bodies);
  }
  
}advance;

struct
{
  struct for_block
  { double &e;
    template<class T> struct foreach_block
    { T &t;
      double &e;
      template<class T2> void operator()(T2& b2)
      {
	auto& b = t.fst;
        double dx = b.x - b2.x;
        double dy = b.y - b2.y;
        double dz = b.z - b2.z;
        double distance = sqrt(dx * dx + dy * dy + dz * dz);
        e -= (b.mass * b2.mass) / distance;
      }  
    };
    
    template<class T> void operator()(T& bodies)
    {
      auto& p = bodies.fst;
      e += 0.5 * p.mass * (p.vx * p.vx + p.vy * p.vy + p.vz * p.vz);
      
      foreach_block<decltype(bodies)> run = {bodies,e};
      FOREACH(run,bodies.snd);
    }
  };

  template<class T> double operator()(T& bodies)
  {
    double e = 0.0;
    for_block run = {e};
    FOR(run,bodies);
    return e;
  }
  
}energy;

struct
{
  struct foreach_block
  {
    double &px, &py, &pz;
    template<class T> void operator()(T& body) 
    {
      px += body.vx * body.mass;
      py += body.vy * body.mass;
      pz += body.vz * body.mass;
    }
  };
  
  template<class T> void operator()(T& bodies)
  {
    double px = 0.0, py = 0.0, pz = 0.0;
    foreach_block run = {px,py,pz};
    FOREACH(run,bodies);
    
    bodies.fst.vx = -px / solar_mass;
    bodies.fst.vy = -py / solar_mass;
    bodies.fst.vz = -pz / solar_mass;
  }
  
}offset;


}

int main(int,char** argv)
{
 
  auto solar_system = construct_tuple(sun,jupiter,saturn,uranus,neptune);
  offset(solar_system);

  printf ("%.9f\n", energy(solar_system));
  
  int n = atoi(argv[1]);
  
  for (int i = 1; i <= n; i++)
  {
    advance(solar_system);
  }

  printf ("%.9f\n", energy(solar_system));

  return 0;
}

 make, command-line, and program output logs

Sun, 20 Apr 2014 22:14:21 GMT

MAKE:
/usr/bin/g++ -c -pipe -O3 -fomit-frame-pointer -march=native -mfpmath=sse -msse3 --std=c++11 nbody.gpp-6.c++ -o nbody.gpp-6.c++.o &&  \
        /usr/bin/g++ nbody.gpp-6.c++.o -o nbody.gpp-6.gpp_run -fopenmp 
rm nbody.gpp-6.c++
0.30s to complete and log all make actions

COMMAND LINE:
./nbody.gpp-6.gpp_run 50000000

PROGRAM OUTPUT:
-0.169075164
-0.169059907

Revised BSD license

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