1 /* The Great Computer Language Shootout
2 http://shootout.alioth.debian.org/
3 contributed by Isaac Gouy */
5 var PI = 3.141592653589793;
6 var SOLAR_MASS = 4 * PI * PI;
7 var DAYS_PER_YEAR = 365.24;
9 function Body(x,y,z,vx,vy,vz,mass){
19 Body.prototype.offsetMomentum = function(px,py,pz) {
20 this.vx = -px / SOLAR_MASS;
21 this.vy = -py / SOLAR_MASS;
22 this.vz = -pz / SOLAR_MASS;
28 4.84143144246472090e+00,
29 -1.16032004402742839e+00,
30 -1.03622044471123109e-01,
31 1.66007664274403694e-03 * DAYS_PER_YEAR,
32 7.69901118419740425e-03 * DAYS_PER_YEAR,
33 -6.90460016972063023e-05 * DAYS_PER_YEAR,
34 9.54791938424326609e-04 * SOLAR_MASS
40 8.34336671824457987e+00,
41 4.12479856412430479e+00,
42 -4.03523417114321381e-01,
43 -2.76742510726862411e-03 * DAYS_PER_YEAR,
44 4.99852801234917238e-03 * DAYS_PER_YEAR,
45 2.30417297573763929e-05 * DAYS_PER_YEAR,
46 2.85885980666130812e-04 * SOLAR_MASS
52 1.28943695621391310e+01,
53 -1.51111514016986312e+01,
54 -2.23307578892655734e-01,
55 2.96460137564761618e-03 * DAYS_PER_YEAR,
56 2.37847173959480950e-03 * DAYS_PER_YEAR,
57 -2.96589568540237556e-05 * DAYS_PER_YEAR,
58 4.36624404335156298e-05 * SOLAR_MASS
64 1.53796971148509165e+01,
65 -2.59193146099879641e+01,
66 1.79258772950371181e-01,
67 2.68067772490389322e-03 * DAYS_PER_YEAR,
68 1.62824170038242295e-03 * DAYS_PER_YEAR,
69 -9.51592254519715870e-05 * DAYS_PER_YEAR,
70 5.15138902046611451e-05 * SOLAR_MASS
75 return new Body(0.0, 0.0, 0.0, 0.0, 0.0, 0.0, SOLAR_MASS);
79 function NBodySystem(bodies){
84 var size = this.bodies.length;
85 for (var i=0; i<size; i++){
86 var b = this.bodies[i];
92 this.bodies[0].offsetMomentum(px,py,pz);
95 NBodySystem.prototype.advance = function(dt){
96 var dx, dy, dz, distance, mag;
97 var size = this.bodies.length;
99 for (var i=0; i<size; i++) {
100 var bodyi = this.bodies[i];
101 for (var j=i+1; j<size; j++) {
102 var bodyj = this.bodies[j];
103 dx = bodyi.x - bodyj.x;
104 dy = bodyi.y - bodyj.y;
105 dz = bodyi.z - bodyj.z;
107 distance = Math.sqrt(dx*dx + dy*dy + dz*dz);
108 mag = dt / (distance * distance * distance);
110 bodyi.vx -= dx * bodyj.mass * mag;
111 bodyi.vy -= dy * bodyj.mass * mag;
112 bodyi.vz -= dz * bodyj.mass * mag;
114 bodyj.vx += dx * bodyi.mass * mag;
115 bodyj.vy += dy * bodyi.mass * mag;
116 bodyj.vz += dz * bodyi.mass * mag;
120 for (var i=0; i<size; i++) {
121 var body = this.bodies[i];
122 body.x += dt * body.vx;
123 body.y += dt * body.vy;
124 body.z += dt * body.vz;
128 NBodySystem.prototype.energy = function(){
129 var dx, dy, dz, distance;
131 var size = this.bodies.length;
133 for (var i=0; i<size; i++) {
134 var bodyi = this.bodies[i];
136 e += 0.5 * bodyi.mass *
137 ( bodyi.vx * bodyi.vx
138 + bodyi.vy * bodyi.vy
139 + bodyi.vz * bodyi.vz );
141 for (var j=i+1; j<size; j++) {
142 var bodyj = this.bodies[j];
143 dx = bodyi.x - bodyj.x;
144 dy = bodyi.y - bodyj.y;
145 dz = bodyi.z - bodyj.z;
147 distance = Math.sqrt(dx*dx + dy*dy + dz*dz);
148 e -= (bodyi.mass * bodyj.mass) / distance;
156 for ( var n = 3; n <= 24; n *= 2 ) {
158 var bodies = new NBodySystem( Array(
159 Sun(),Jupiter(),Saturn(),Uranus(),Neptune()
163 ret = bodies.energy();
164 for (var i=0; i<max; i++){
165 bodies.advance(0.01);
167 ret = bodies.energy();
171 assertEq(ret, -0.16906933525822856)