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nbody2.jl.mem
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nbody2.jl.mem
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- # N-body simulation
- # Based off of the Computer Language Benchmarks Game
-
- using Printf
- using LinearAlgebra
- using StaticArrays
- using Profile
-
- # Constants
- const SOLAR_MASS = 4*pi*pi
- const DAYS_PER_YEAR = 365.24
-
- # Body type
- mutable struct Body
38028 x::MVector{3,Float64}
- fill::Float64
- v::MVector{3,Float64}
- mass::Float64
- end
-
- # Define each of the body initial values
- _bodies = MVector(
- # Sun
- Body(MVector(0.0, 0.0, 0.0),
- 0.0,
- MVector(0.0, 0.0, 0.0),
- SOLAR_MASS),
- # Jupiter
- Body(MVector(4.84143144246472090e+00,
- -1.16032004402742839e+00,
- -1.03622044471123109e-01),
- 0.0,
- MVector(1.66007664274403694e-03 * DAYS_PER_YEAR,
- 7.69901118419740425e-03 * DAYS_PER_YEAR,
- -6.90460016972063023e-05 * DAYS_PER_YEAR),
- 9.54791938424326609e-04 * SOLAR_MASS),
- # Saturn
- Body(MVector(8.34336671824457987e+00,
- 4.12479856412430479e+00,
- -4.03523417114321381e-01),
- 0.0,
- MVector(-2.76742510726862411e-03 * DAYS_PER_YEAR,
- 4.99852801234917238e-03 * DAYS_PER_YEAR,
- 2.30417297573763929e-05 * DAYS_PER_YEAR),
- 2.85885980666130812e-04 * SOLAR_MASS),
- # Uranus
- Body(MVector(1.28943695621391310e+01,
- -1.51111514016986312e+01,
- -2.23307578892655734e-01),
- 0.0,
- MVector(2.96460137564761618e-03 * DAYS_PER_YEAR,
- 2.37847173959480950e-03 * DAYS_PER_YEAR,
- -2.96589568540237556e-05 * DAYS_PER_YEAR),
- 4.36624404335156298e-05 * SOLAR_MASS),
- # Neptune
- Body(MVector(1.53796971148509165e+01,
- -2.59193146099879641e+01,
- 1.79258772950371181e-01),
- 0.0,
- MVector(2.68067772490389322e-03 * DAYS_PER_YEAR,
- 1.62824170038242295e-03 * DAYS_PER_YEAR,
- -9.51592254519715870e-05 * DAYS_PER_YEAR),
- 5.15138902046611451e-05 * SOLAR_MASS),
- )
-
- # Pre-define some arrays and values globally to reduce the amount of copying
- # dx = zeros(3)
-
- """
- Not sure exactly what this is supposed to be doing
- """
- function offset_momentum!(bodies)
5441492 for i = 1:length(bodies)
0 @. bodies[1].v -= bodies[i].v * (bodies[i].mass / SOLAR_MASS)
- end
- end
-
- """
- Advance the positions and velocities
- """
- function bodies_advance!(bodies,dt::Float64)
- dx = @MVector zeros(3)
- dsq = 0.
- distance = 0.
0 mag = 0.
-
0 for i = 1:length(bodies)
- for j = (i+1):length(bodies)
- @. dx = bodies[i].x - bodies[j].x
-
- dsq = dot(dx, dx)
- distance = sqrt(dsq)
- mag = dt / (dsq * distance)
-
0 @. bodies[i].v -= dx * bodies[j].mass * mag
0 @. bodies[j].v += dx * bodies[i].mass * mag
- end
- end
-
0 for k = 1:length(bodies)
- @. bodies[k].x += dt * bodies[k].v
- end
- end
-
- """
- Compute the overall energy in the system
- """
- function bodies_energy(bodies)
- dx = @MVector zeros(3)
- distance = 0.
0 energy = 0.
-
- for i = 1:length(bodies)
0 energy += bodies[i].mass * dot(bodies[i].v, bodies[i].v) / 2.0
-
- for j = (i+1):length(bodies)
- @. dx = bodies[i].x - bodies[j].x
-
0 distance = norm(dx)
0 energy -= (bodies[i].mass * bodies[j].mass) / distance
- end
- end
- return energy
- end
-
-
- function main_loop(bodies,N::Int64)
-
0 offset_momentum!(bodies)
-
5436398 @printf "%.9f\n" bodies_energy(bodies)
-
144 for i = 1:N; bodies_advance!(bodies,0.01); end
-
0 @printf "%.9f\n" bodies_energy(bodies)
-
- end
-
- # N = 10000
- N = 5000000
- if length(ARGS) >= 1
- N = parse(Int64, ARGS[1])
- end
-
- # @profile main_loop(_bodies,N)
- @time main_loop(_bodies,N)
- # main_loop(_bodies,N-1)
- # Profile.print()
-