The Computer Language
Benchmarks Game

n-body TypeScript program

source code

/* The Computer Language Benchmarks Game
   http://benchmarksgame.alioth.debian.org/
   contributed by Isaac Gouy 

   Transliterated from Smalltalk program
*/


/// <reference path="./Include/node/index.d.ts" />

class PlanetarySystem {
   private bodies: Body[]

   constructor(){
      this.bodies = [
         Body.Sun(),		
         Body.Jupiter(),
         Body.Saturn(),
         Body.Uranus(),
         Body.Neptune()
      ]

      // How to use reduce?
      let total : [number,number,number] = [0.0,0.0,0.0]	
      this.bodies.forEach(each => {
         total = each.addMomentumTo(total)
      })
      this.bodies[0].offsetMomentum(total)
   }

   after(dt: number) {
      const size = this.bodies.length
      for (let i=0; i<size; i++) {
         for (let j=i+1; j < size; j++) {	
            this.bodies[i].setVelocitiesAfter(dt,this.bodies[j])
         }
      }
      for (let i=0; i<size; i++) {	
         this.bodies[i].setPositionAfter(dt)	
      }
   }

   energy(): number {
      let e = 0.0
      const size = this.bodies.length
      for (let i=0; i<size; i++) {
         e += this.bodies[i].kineticEnergy()
         for (let j=i+1; j < size; j++) {	
            e -= this.bodies[i].potentialEnergyWith(this.bodies[j])
         }
      }
      return e
   }
}


class Body {
   private static PI = 3.141592653589793
   private static SOLAR_MASS = 4 * Body.PI * Body.PI
   private static DAYS_PER_YEAR = 365.24

   constructor(
      private x: number, 
      private y: number, 
      private z: number, 
      private vx: number,
      private vy: number, 
      private vz: number,
      private m: number
   ) { }

   mass(): number {
      return this.m
   }

   static Jupiter(){
      return new Body(
         4.84143144246472090e+00,
         -1.16032004402742839e+00,
         -1.03622044471123109e-01,
         1.66007664274403694e-03 * Body.DAYS_PER_YEAR,
         7.69901118419740425e-03 * Body.DAYS_PER_YEAR,
         -6.90460016972063023e-05 * Body.DAYS_PER_YEAR,
         9.54791938424326609e-04 * Body.SOLAR_MASS
      )
   }

   static Saturn(){
      return new Body(
         8.34336671824457987e+00,
         4.12479856412430479e+00,
         -4.03523417114321381e-01,
         -2.76742510726862411e-03 * Body.DAYS_PER_YEAR,
         4.99852801234917238e-03 * Body.DAYS_PER_YEAR,
         2.30417297573763929e-05 * Body.DAYS_PER_YEAR,
         2.85885980666130812e-04 * Body.SOLAR_MASS
      )
   }

   static Uranus(){
      return new Body(
         1.28943695621391310e+01,
         -1.51111514016986312e+01,
         -2.23307578892655734e-01,
         2.96460137564761618e-03 * Body.DAYS_PER_YEAR,
         2.37847173959480950e-03 * Body.DAYS_PER_YEAR,
         -2.96589568540237556e-05 * Body.DAYS_PER_YEAR,
         4.36624404335156298e-05 * Body.SOLAR_MASS
      )
   }

   static Neptune(){
      return new Body(
         1.53796971148509165e+01,
         -2.59193146099879641e+01,
         1.79258772950371181e-01,
         2.68067772490389322e-03 * Body.DAYS_PER_YEAR,
         1.62824170038242295e-03 * Body.DAYS_PER_YEAR,
         -9.51592254519715870e-05 * Body.DAYS_PER_YEAR,
         5.15138902046611451e-05 * Body.SOLAR_MASS
      )
   }

   static Sun(){
      return new Body(
         0,
         0,
         0,
         0,
         0,
         0,
         Body.SOLAR_MASS
      )
   }


   addMomentumTo([x,y,z]: [number,number,number]): [number,number,number] {
      return [
         x + this.vx * this.m, 
         y + this.vy * this.m, 
         z + this.vz * this.m 
         ]
   }

   private decreaseVelocity(dx, dy, dz, m: number) {
      this.vx -= dx * m
      this.vy -= dy * m
      this.vz -= dz * m
   }

   private increaseVelocity(dx, dy, dz, m : number) {
      this.vx += dx * m
      this.vy += dy * m
      this.vz += dz * m
   }

   kineticEnergy(): number {
      return 0.5 * this.m * (this.vx**2 + this.vy**2 + this.vz**2)
   }

   offsetMomentum([px,py,pz]: [number,number,number]) {
      this.vx = -px / Body.SOLAR_MASS
      this.vy = -py / Body.SOLAR_MASS
      this.vz = -pz / Body.SOLAR_MASS  
   }

   potentialEnergyWith(b: Body) {
      const [dx,dy,dz] = b.vectorTo(this.x,this.y,this.z)
      const distance = Math.sqrt(dx**2 + dy**2 + dz**2)
      return this.m * b.mass() / distance
   }

   setPositionAfter(dt: number) {
      this.x += dt * this.vx
      this.y += dt * this.vy
      this.z += dt * this.vz
   }

   setVelocitiesAfter(dt: number, b: Body) {
      const [dx,dy,dz] = b.vectorTo(this.x,this.y,this.z)
      const distance = Math.sqrt(dx**2 + dy**2 + dz**2)
      const mag = dt / distance**3
      this.decreaseVelocity(dx,dy,dz,b.mass()*mag)
      b.increaseVelocity(dx,dy,dz,this.m*mag)
   }

   private vectorTo(x,y,z : number) {
      return [x-this.x, y-this.y, z-this.z]
   }
}


const n = +process.argv[2]
const system = new PlanetarySystem()
console.log(system.energy().toFixed(9))
for (let i=0; i<n; i++){ system.after(0.01) }
console.log(system.energy().toFixed(9))

    

notes, command-line, and program output

NOTES:
64-bit Ubuntu quad core
Version 2.2.1
node.js v7.6.0


Thu, 23 Feb 2017 18:08:35 GMT

MAKE:
mv nbody.typescript nbody.ts
/usr/local/src/node-v7.6.0-linux-x64/bin/tsc --alwaysStrict -t ESNEXT  nbody.ts
1.67s to complete and log all make actions

COMMAND LINE:
/usr/local/src/node-v7.6.0-linux-x64/bin/node --use_strict nbody.js 50000000

PROGRAM OUTPUT:
-0.169075164
-0.169059907