add benchmarks

benchmarks/nbody.ce

@@ -0,0 +1,161 @@
+var PI = Math.PI;
+var SOLAR_MASS = 4 * PI * PI;
+var 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);
+}
+
+var bodies = Array(Sun(), Jupiter(), Saturn(), Uranus(), Neptune());
+
+function offsetMomentum() {
+    let px = 0;
+    let py = 0;
+    let pz = 0;
+    var size = bodies.length;
+    for (let i = 0; i < size; i++) {
+        var body = bodies[i];
+        var mass = body.mass;
+        px += body.vx * mass;
+        py += body.vy * mass;
+        pz += body.vz * mass;
+    }
+
+    var body = bodies[0];
+    body.vx = -px / SOLAR_MASS;
+    body.vy = -py / SOLAR_MASS;
+    body.vz = -pz / SOLAR_MASS;
+}
+
+function advance(dt) {
+    var size = bodies.length;
+
+    for (let i = 0; i < size; i++) {
+        var bodyi = bodies[i];
+        let vxi = bodyi.vx;
+        let vyi = bodyi.vy;
+        let vzi = bodyi.vz;
+        for (let j = i + 1; j < size; j++) {
+            var bodyj = bodies[j];
+            var dx = bodyi.x - bodyj.x;
+            var dy = bodyi.y - bodyj.y;
+            var dz = bodyi.z - bodyj.z;
+
+            var d2 = dx * dx + dy * dy + dz * dz;
+            var mag = dt / (d2 * Math.sqrt(d2));
+
+            var massj = bodyj.mass;
+            vxi -= dx * massj * mag;
+            vyi -= dy * massj * mag;
+            vzi -= dz * massj * mag;
+
+            var 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++) {
+        var body = bodies[i];
+        body.x += dt * body.vx;
+        body.y += dt * body.vy;
+        body.z += dt * body.vz;
+    }
+}
+
+function energy() {
+    let e = 0;
+    var size = bodies.length;
+
+    for (let i = 0; i < size; i++) {
+        var 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++) {
+            var bodyj = bodies[j];
+            var dx = bodyi.x - bodyj.x;
+            var dy = bodyi.y - bodyj.y;
+            var dz = bodyi.z - bodyj.z;
+
+            var distance = Math.sqrt(dx * dx + dy * dy + dz * dz);
+            e -= (bodyi.mass * bodyj.mass) / distance;
+        }
+    }
+    return e;
+}
+
+var n = arg[0] || 1000000
+
+offsetMomentum();
+
+log.console(`n = ${n}`)
+log.console(energy().toFixed(9))
+for (let i = 0; i < n; i++)
+    advance(0.01);
+log.console(energy().toFixed(9))
+
+$_.stop()