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Roblox
GitHub Repository: Roblox/luau
 Path: blob/master/bench/tests/shootout/n-body.lua
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local function prequire(name) local success, result = pcall(require, name); return success and result end

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local bench = script and require(script.Parent.bench_support) or prequire("bench_support") or require("../../bench_support")

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function test()

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    --The Computer Language Benchmarks Game

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    -- https://salsa.debian.org/benchmarksgame-team/benchmarksgame/

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    --contributed by Mike Pall

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    local PI = 3.141592653589793

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    local SOLAR_MASS = 4 * PI * PI

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    local DAYS_PER_YEAR = 365.24

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    local bodies = {

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        { --Sun

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        x = 0,

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        y = 0,

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        z = 0,

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        vx = 0,

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        vy = 0,

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        vz = 0,

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        mass = SOLAR_MASS

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        },

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        { --Jupiter

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        x = 4.84143144246472090e+00,

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        y = -1.16032004402742839e+00,

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        z = -1.03622044471123109e-01,

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        vx = 1.66007664274403694e-03 * DAYS_PER_YEAR,

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        vy = 7.69901118419740425e-03 * DAYS_PER_YEAR,

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        vz = -6.90460016972063023e-05 * DAYS_PER_YEAR,

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        mass = 9.54791938424326609e-04 * SOLAR_MASS

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        },

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        { --Saturn

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        x = 8.34336671824457987e+00,

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        y = 4.12479856412430479e+00,

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        z = -4.03523417114321381e-01,

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        vx = -2.76742510726862411e-03 * DAYS_PER_YEAR,

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        vy = 4.99852801234917238e-03 * DAYS_PER_YEAR,

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        vz = 2.30417297573763929e-05 * DAYS_PER_YEAR,

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        mass = 2.85885980666130812e-04 * SOLAR_MASS

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        },

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        { --Uranus

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        x = 1.28943695621391310e+01,

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        y = -1.51111514016986312e+01,

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        z = -2.23307578892655734e-01,

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        vx = 2.96460137564761618e-03 * DAYS_PER_YEAR,

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        vy = 2.37847173959480950e-03 * DAYS_PER_YEAR,

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        vz = -2.96589568540237556e-05 * DAYS_PER_YEAR,

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        mass = 4.36624404335156298e-05 * SOLAR_MASS

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        },

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        { --Neptune

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        x = 1.53796971148509165e+01,

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        y = -2.59193146099879641e+01,

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        z = 1.79258772950371181e-01,

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        vx = 2.68067772490389322e-03 * DAYS_PER_YEAR,

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        vy = 1.62824170038242295e-03 * DAYS_PER_YEAR,

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        vz = -9.51592254519715870e-05 * DAYS_PER_YEAR,

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        mass = 5.15138902046611451e-05 * SOLAR_MASS

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        }

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    }

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    local function advance(bodies, nbody, dt)

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        for i = 1, nbody do

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            local bi = bodies[i]

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            local bix, biy, biz, bimass = bi.x, bi.y, bi.z, bi.mass

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            local bivx, bivy, bivz = bi.vx, bi.vy, bi.vz

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            for j = i + 1, nbody do

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                local bj = bodies[j]

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                local dx, dy, dz = bix - bj.x, biy - bj.y, biz - bj.z

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                local distance = math.sqrt(dx*dx + dy*dy + dz*dz)

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                local mag = dt / (distance * distance * distance)

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                local bim, bjm = bimass*mag, bj.mass*mag

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                bivx = bivx - (dx * bjm)

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                bivy = bivy - (dy * bjm)

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                bivz = bivz - (dz * bjm)

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                bj.vx = bj.vx + (dx * bim)

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                bj.vy = bj.vy + (dy * bim)

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                bj.vz = bj.vz + (dz * bim)

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            end

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            bi.vx = bivx

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            bi.vy = bivy

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            bi.vz = bivz

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        end

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        for i = 1, nbody do

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            local bi = bodies[i]

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            bi.x = bi.x + (dt * bi.vx)

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            bi.y = bi.y + (dt * bi.vy)

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            bi.z = bi.z + (dt * bi.vz)

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        end

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    end

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    local function energy(bodies, nbody)

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        local e = 0

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        for i = 1, nbody do

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            local bi = bodies[i]

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            local vx, vy, vz, bim = bi.vx, bi.vy, bi.vz, bi.mass

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            e = e + (0.5 * bim * (vx*vx + vy*vy + vz*vz))

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            for j = i + 1, nbody do

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                local bj = bodies[j]

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                local dx, dy, dz = bi.x - bj.x, bi.y - bj.y, bi.z - bj.z

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                local distance = math.sqrt(dx*dx + dy*dy + dz*dz)

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                e = e - ((bim * bj.mass) / distance)

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            end

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        end

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        return e

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    end

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    local function offsetMomentum(b, nbody)

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        local px, py, pz = 0, 0, 0

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        for i = 1, nbody do

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            local bi = b[i]

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            local bim = bi.mass

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            px = px + (bi.vx * bim)

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            py = py + (bi.vy * bim)

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            pz = pz + (bi.vz * bim)

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        end

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        b[1].vx = -px / SOLAR_MASS

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        b[1].vy = -py / SOLAR_MASS

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        b[1].vz = -pz / SOLAR_MASS

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    end

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    local N = 20000

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    local nbody = #bodies

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    local ts0 = os.clock()

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    offsetMomentum(bodies, nbody)

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    for i = 1, N do advance(bodies, nbody, 0.01) end

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    local ts1 = os.clock()

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    return ts1 - ts0

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end

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bench.runCode(test, "n-body")

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