source code
/* The Computer Language Benchmarks Game
https://salsa.debian.org/benchmarksgame-team/benchmarksgame/
contributed by Isaac Gouy, optimization and use of more C# idioms by Robert F. Tobler
*/
using System;
class NBody {
public static void Main(String[] args) {
int n = args.Length > 0 ? Int32.Parse(args[0]) : 10000;
NBodySystem bodies = new NBodySystem();
Console.WriteLine("{0:f9}", bodies.Energy());
for (int i = 0; i < n; i++) bodies.Advance(0.01);
Console.WriteLine("{0:f9}", bodies.Energy());
}
}
class Body { public double x, y, z, vx, vy, vz, mass; }
class Pair { public Body bi, bj; }
class NBodySystem {
private Body[] bodies;
private Pair[] pairs;
const double Pi = 3.141592653589793;
const double Solarmass = 4 * Pi * Pi;
const double DaysPeryear = 365.24;
public NBodySystem() {
bodies = new Body[] {
new Body() { // Sun
mass = Solarmass,
},
new Body() { // Jupiter
x = 4.84143144246472090e+00,
y = -1.16032004402742839e+00,
z = -1.03622044471123109e-01,
vx = 1.66007664274403694e-03 * DaysPeryear,
vy = 7.69901118419740425e-03 * DaysPeryear,
vz = -6.90460016972063023e-05 * DaysPeryear,
mass = 9.54791938424326609e-04 * Solarmass,
},
new Body() { // Saturn
x = 8.34336671824457987e+00,
y = 4.12479856412430479e+00,
z = -4.03523417114321381e-01,
vx = -2.76742510726862411e-03 * DaysPeryear,
vy = 4.99852801234917238e-03 * DaysPeryear,
vz = 2.30417297573763929e-05 * DaysPeryear,
mass = 2.85885980666130812e-04 * Solarmass,
},
new Body() { // Uranus
x = 1.28943695621391310e+01,
y = -1.51111514016986312e+01,
z = -2.23307578892655734e-01,
vx = 2.96460137564761618e-03 * DaysPeryear,
vy = 2.37847173959480950e-03 * DaysPeryear,
vz = -2.96589568540237556e-05 * DaysPeryear,
mass = 4.36624404335156298e-05 * Solarmass,
},
new Body() { // Neptune
x = 1.53796971148509165e+01,
y = -2.59193146099879641e+01,
z = 1.79258772950371181e-01,
vx = 2.68067772490389322e-03 * DaysPeryear,
vy = 1.62824170038242295e-03 * DaysPeryear,
vz = -9.51592254519715870e-05 * DaysPeryear,
mass = 5.15138902046611451e-05 * Solarmass,
},
};
pairs = new Pair[bodies.Length * (bodies.Length-1)/2];
int pi = 0;
for (int i = 0; i < bodies.Length-1; i++)
for (int j = i+1; j < bodies.Length; j++)
pairs[pi++] = new Pair() { bi = bodies[i], bj = bodies[j] };
double px = 0.0, py = 0.0, pz = 0.0;
foreach (var b in bodies) {
px += b.vx * b.mass; py += b.vy * b.mass; pz += b.vz * b.mass;
}
var sol = bodies[0];
sol.vx = -px/Solarmass; sol.vy = -py/Solarmass; sol.vz = -pz/Solarmass;
}
public void Advance(double dt) {
foreach (var p in pairs) {
Body bi = p.bi, bj = p.bj;
double dx = bi.x - bj.x, dy = bi.y - bj.y, dz = bi.z - bj.z;
double d2 = dx * dx + dy * dy + dz * dz;
double mag = dt / (d2 * Math.Sqrt(d2));
bi.vx -= dx * bj.mass * mag; bj.vx += dx * bi.mass * mag;
bi.vy -= dy * bj.mass * mag; bj.vy += dy * bi.mass * mag;
bi.vz -= dz * bj.mass * mag; bj.vz += dz * bi.mass * mag;
}
foreach (var b in bodies) {
b.x += dt * b.vx; b.y += dt * b.vy; b.z += dt * b.vz;
}
}
public double Energy() {
double e = 0.0;
for (int i = 0; i < bodies.Length; i++) {
var bi = bodies[i];
e += 0.5 * bi.mass * (bi.vx*bi.vx + bi.vy*bi.vy + bi.vz*bi.vz);
for (int j = i+1; j < bodies.Length; j++) {
var bj = bodies[j];
double dx = bi.x - bj.x, dy = bi.y - bj.y, dz = bi.z - bj.z;
e -= (bi.mass * bj.mass) / Math.Sqrt(dx*dx + dy*dy + dz*dz);
}
}
return e;
}
}
notes, command-line, and program output
NOTES:
64-bit Ubuntu quad core
.NET SDK 8.0.204
Host Version: 8.0.4
Commit: 2d7eea2529
<AllowUnsafeBlocks>true
<ServerGarbageCollection>true
<ConcurrentGarbageCollection>true
<PublishAot>false
<OptimizationPreference>Speed
<IlcInstructionSet>native
Fri, 26 Apr 2024 01:01:37 GMT
MAKE:
cp nbody.csharpcore-3.csharpcore Program.cs
cp Include/csharpcore/program.csproj .
mkdir obj
cp Include/csharpcore/project.assets.json ./obj
/usr/bin/dotnet build -c Release --use-current-runtime
MSBuild version 17.9.8+b34f75857 for .NET
Determining projects to restore...
Restored /home/dunham/all-benchmarksgame/benchmarksgame_i53330/nbody/tmp/program.csproj (in 181 ms).
/home/dunham/all-benchmarksgame/benchmarksgame_i53330/nbody/tmp/Program.cs(20,26): warning CS8618: Non-nullable field 'bi' must contain a non-null value when exiting constructor. Consider declaring the field as nullable. [/home/dunham/all-benchmarksgame/benchmarksgame_i53330/nbody/tmp/program.csproj]
/home/dunham/all-benchmarksgame/benchmarksgame_i53330/nbody/tmp/Program.cs(20,30): warning CS8618: Non-nullable field 'bj' must contain a non-null value when exiting constructor. Consider declaring the field as nullable. [/home/dunham/all-benchmarksgame/benchmarksgame_i53330/nbody/tmp/program.csproj]
program -> /home/dunham/all-benchmarksgame/benchmarksgame_i53330/nbody/tmp/bin/Release/net8.0/linux-x64/program.dll
Build succeeded.
/home/dunham/all-benchmarksgame/benchmarksgame_i53330/nbody/tmp/Program.cs(20,26): warning CS8618: Non-nullable field 'bi' must contain a non-null value when exiting constructor. Consider declaring the field as nullable. [/home/dunham/all-benchmarksgame/benchmarksgame_i53330/nbody/tmp/program.csproj]
/home/dunham/all-benchmarksgame/benchmarksgame_i53330/nbody/tmp/Program.cs(20,30): warning CS8618: Non-nullable field 'bj' must contain a non-null value when exiting constructor. Consider declaring the field as nullable. [/home/dunham/all-benchmarksgame/benchmarksgame_i53330/nbody/tmp/program.csproj]
2 Warning(s)
0 Error(s)
Time Elapsed 00:00:03.96
5.52s to complete and log all make actions
COMMAND LINE:
./bin/Release/net8.0/linux-x64/program 50000000
PROGRAM OUTPUT:
-0.169075164
-0.169059907