source code
/* The Computer Language Benchmarks Game
contributed by Isaac Gouy
modified by TVSori None
converted to Swift 3 by Sergo Beruashvili
optimized by Hannes Sverrisson
*/
import Foundation
struct Body {
var x, y, z, vx, vy, vz, mass : Double
@inline(__always)
public mutating func velSub(dx: Double, dy: Double, dz: Double, mass: Double) {
self.vx -= dx * mass
self.vy -= dy * mass
self.vz -= dz * mass
}
@inline(__always)
public mutating func velAdd(dx: Double, dy: Double, dz: Double, mass: Double) {
self.vx += dx * mass
self.vy += dy * mass
self.vz += dz * mass
}
@inline(__always)
public mutating func distAdd() {
self.x += self.vx * 0.01
self.y += self.vy * 0.01
self.z += self.vz * 0.01
}
}
let PI: Double = 3.14159265358979
let SOLAR_MASS: Double = 4 * PI * PI
let DAYS_PER_YEAR: Double = 365.24
let bodies: [Body] = [
Body (
x: 0.0,
y: 0.0,
z: 0.0,
vx: 0.0,
vy: 0.0,
vz: 0.0,
mass: SOLAR_MASS
),
Body (
x: 4.84143144246472090e+00,
y: -1.16032004402742839e+00,
z: -1.03622044471123109e-01,
vx: 1.66007664274403694e-03 * DAYS_PER_YEAR,
vy: 7.69901118419740425e-03 * DAYS_PER_YEAR,
vz: -6.90460016972063023e-05 * DAYS_PER_YEAR,
mass: 9.54791938424326609e-04 * SOLAR_MASS
),
Body (
x: 8.34336671824457987e+00,
y: 4.12479856412430479e+00,
z: -4.03523417114321381e-01,
vx: -2.76742510726862411e-03 * DAYS_PER_YEAR,
vy: 4.99852801234917238e-03 * DAYS_PER_YEAR,
vz: 2.30417297573763929e-05 * DAYS_PER_YEAR,
mass: 2.85885980666130812e-04 * SOLAR_MASS
),
Body (
x: 1.28943695621391310e+01,
y: -1.51111514016986312e+01,
z: -2.23307578892655734e-01,
vx: 2.96460137564761618e-03 * DAYS_PER_YEAR,
vy: 2.37847173959480950e-03 * DAYS_PER_YEAR,
vz: -2.96589568540237556e-05 * DAYS_PER_YEAR,
mass: 4.36624404335156298e-05 * SOLAR_MASS
),
Body (
x: 1.53796971148509165e+01,
y: -2.59193146099879641e+01,
z: 1.79258772950371181e-01,
vx: 2.68067772490389322e-03 * DAYS_PER_YEAR,
vy: 1.62824170038242295e-03 * DAYS_PER_YEAR,
vz: -9.51592254519715870e-05 * DAYS_PER_YEAR,
mass: 5.15138902046611451e-05 * SOLAR_MASS
)
]
func offsetMomentum() {
var px: Double = 0.0
var py: Double = 0.0
var pz: Double = 0.0
for body in bodies {
px += body.vx * body.mass
py += body.vy * body.mass
pz += body.vz * body.mass
}
let bodiesPtr = UnsafeMutablePointer<Body>(mutating: bodies)
bodiesPtr[0].vx = -px / SOLAR_MASS
bodiesPtr[0].vy = -py / SOLAR_MASS
bodiesPtr[0].vz = -pz / SOLAR_MASS
}
func energy() -> Double {
var dx, dy, dz, distance: Double
var e: Double = 0.0
for i in 0..<5 {
let body = bodies[i]
e += 0.5 * body.mass *
( body.vx * body.vx
+ body.vy * body.vy
+ body.vz * body.vz )
for j in i+1..<5 {
let jbody = bodies[j]
dx = body.x - jbody.x
dy = body.y - jbody.y
dz = body.z - jbody.z
distance = sqrt(dx*dx + dy*dy + dz*dz)
e -= (body.mass * jbody.mass) / distance
}
}
return e
}
func advance(n: Int) {
for _ in 1...n {
var dx, dy, dz, distance, mag: Double
let arrPtr = UnsafeMutablePointer<Body>(mutating: bodies)
for i in 0..<5 {
let body = bodies[i]
for j in (i+1)..<5 {
let jbody = bodies[j]
dx = body.x - jbody.x
dy = body.y - jbody.y
dz = body.z - jbody.z
distance = dx * dx + dy * dy + dz * dz
mag = 0.01 / (distance * sqrt(distance))
arrPtr[i].velSub(dx: dx, dy: dy, dz: dz, mass: jbody.mass * mag)
arrPtr[j].velAdd(dx: dx, dy: dy, dz: dz, mass: body.mass * mag)
}
arrPtr[i].distAdd()
}
}
}
let n: Int = Int(CommandLine.arguments[1]) ?? 50_000_000
offsetMomentum()
print(String(format: "%0.9f", Double(energy())))
advance(n: n)
print(String(format: "%0.9f", Double(energy())))