source code
/* The Computer Language Benchmarks Game
https://salsa.debian.org/benchmarksgame-team/benchmarksgame/
contributed by Isaac Gouy
modified by Andrey Filatkin */
const PI = Math.PI;
const SOLAR_MASS = 4 * PI * PI;
const DAYS_PER_YEAR = 365.24;
function Body(x, y, z, vx, vy, vz, mass) {
this.x = x;
this.y = y;
this.z = z;
this.vx = vx;
this.vy = vy;
this.vz = vz;
this.mass = mass;
}
function Jupiter() {
return new Body(
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
);
}
function Saturn() {
return new Body(
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
);
}
function Uranus() {
return new Body(
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
);
}
function Neptune() {
return new Body(
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
);
}
function Sun() {
return new Body(0.0, 0.0, 0.0, 0.0, 0.0, 0.0, SOLAR_MASS);
}
const bodies = Array(Sun(), Jupiter(), Saturn(), Uranus(), Neptune());
function offsetMomentum() {
let px = 0;
let py = 0;
let pz = 0;
const size = bodies.length;
for (let i = 0; i < size; i++) {
const body = bodies[i];
const mass = body.mass;
px += body.vx * mass;
py += body.vy * mass;
pz += body.vz * mass;
}
const body = bodies[0];
body.vx = -px / SOLAR_MASS;
body.vy = -py / SOLAR_MASS;
body.vz = -pz / SOLAR_MASS;
}
function advance(dt) {
const size = bodies.length;
for (let i = 0; i < size; i++) {
const bodyi = bodies[i];
let vxi = bodyi.vx;
let vyi = bodyi.vy;
let vzi = bodyi.vz;
for (let j = i + 1; j < size; j++) {
const bodyj = bodies[j];
const dx = bodyi.x - bodyj.x;
const dy = bodyi.y - bodyj.y;
const dz = bodyi.z - bodyj.z;
const d2 = dx * dx + dy * dy + dz * dz;
const mag = dt / (d2 * Math.sqrt(d2));
const massj = bodyj.mass;
vxi -= dx * massj * mag;
vyi -= dy * massj * mag;
vzi -= dz * massj * mag;
const massi = bodyi.mass;
bodyj.vx += dx * massi * mag;
bodyj.vy += dy * massi * mag;
bodyj.vz += dz * massi * mag;
}
bodyi.vx = vxi;
bodyi.vy = vyi;
bodyi.vz = vzi;
}
for (let i = 0; i < size; i++) {
const body = bodies[i];
body.x += dt * body.vx;
body.y += dt * body.vy;
body.z += dt * body.vz;
}
}
function energy() {
let e = 0;
const size = bodies.length;
for (let i = 0; i < size; i++) {
const bodyi = bodies[i];
e += 0.5 * bodyi.mass * ( bodyi.vx * bodyi.vx +
bodyi.vy * bodyi.vy + bodyi.vz * bodyi.vz );
for (let j = i + 1; j < size; j++) {
const bodyj = bodies[j];
const dx = bodyi.x - bodyj.x;
const dy = bodyi.y - bodyj.y;
const dz = bodyi.z - bodyj.z;
const distance = Math.sqrt(dx * dx + dy * dy + dz * dz);
e -= (bodyi.mass * bodyj.mass) / distance;
}
}
return e;
}
const n = +process.argv[2];
offsetMomentum();
console.log(energy().toFixed(9));
for (let i = 0; i < n; i++) {
advance(0.01);
}
console.log(energy().toFixed(9));