зеркало из https://github.com/github/ruby.git
149 строки
2.9 KiB
Ruby
149 строки
2.9 KiB
Ruby
# The Computer Language Shootout
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# http://shootout.alioth.debian.org
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#
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# Optimized for Ruby by Jesse Millikan
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# From version ported by Michael Neumann from the C gcc version,
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# which was written by Christoph Bauer.
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SOLAR_MASS = 4 * Math::PI**2
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DAYS_PER_YEAR = 365.24
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def _puts *args
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end
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class Planet
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attr_accessor :x, :y, :z, :vx, :vy, :vz, :mass
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def initialize(x, y, z, vx, vy, vz, mass)
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@x, @y, @z = x, y, z
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@vx, @vy, @vz = vx * DAYS_PER_YEAR, vy * DAYS_PER_YEAR, vz * DAYS_PER_YEAR
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@mass = mass * SOLAR_MASS
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end
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def move_from_i(bodies, nbodies, dt, i)
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while i < nbodies
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b2 = bodies[i]
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dx = @x - b2.x
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dy = @y - b2.y
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dz = @z - b2.z
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distance = Math.sqrt(dx * dx + dy * dy + dz * dz)
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mag = dt / (distance * distance * distance)
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b_mass_mag, b2_mass_mag = @mass * mag, b2.mass * mag
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@vx -= dx * b2_mass_mag
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@vy -= dy * b2_mass_mag
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@vz -= dz * b2_mass_mag
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b2.vx += dx * b_mass_mag
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b2.vy += dy * b_mass_mag
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b2.vz += dz * b_mass_mag
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i += 1
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end
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@x += dt * @vx
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@y += dt * @vy
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@z += dt * @vz
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end
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end
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def energy(bodies)
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e = 0.0
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nbodies = bodies.size
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for i in 0 ... nbodies
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b = bodies[i]
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e += 0.5 * b.mass * (b.vx * b.vx + b.vy * b.vy + b.vz * b.vz)
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for j in (i + 1) ... nbodies
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b2 = bodies[j]
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dx = b.x - b2.x
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dy = b.y - b2.y
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dz = b.z - b2.z
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distance = Math.sqrt(dx * dx + dy * dy + dz * dz)
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e -= (b.mass * b2.mass) / distance
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end
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end
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e
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end
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def offset_momentum(bodies)
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px, py, pz = 0.0, 0.0, 0.0
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for b in bodies
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m = b.mass
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px += b.vx * m
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py += b.vy * m
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pz += b.vz * m
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end
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b = bodies[0]
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b.vx = - px / SOLAR_MASS
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b.vy = - py / SOLAR_MASS
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b.vz = - pz / SOLAR_MASS
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end
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BODIES = [
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# sun
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Planet.new(0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 1.0),
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# jupiter
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Planet.new(
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4.84143144246472090e+00,
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-1.16032004402742839e+00,
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-1.03622044471123109e-01,
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1.66007664274403694e-03,
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7.69901118419740425e-03,
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-6.90460016972063023e-05,
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9.54791938424326609e-04),
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# saturn
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Planet.new(
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8.34336671824457987e+00,
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4.12479856412430479e+00,
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-4.03523417114321381e-01,
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-2.76742510726862411e-03,
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4.99852801234917238e-03,
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2.30417297573763929e-05,
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2.85885980666130812e-04),
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# uranus
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Planet.new(
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1.28943695621391310e+01,
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-1.51111514016986312e+01,
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-2.23307578892655734e-01,
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2.96460137564761618e-03,
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2.37847173959480950e-03,
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-2.96589568540237556e-05,
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4.36624404335156298e-05),
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# neptune
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Planet.new(
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1.53796971148509165e+01,
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-2.59193146099879641e+01,
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1.79258772950371181e-01,
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2.68067772490389322e-03,
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1.62824170038242295e-03,
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-9.51592254519715870e-05,
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5.15138902046611451e-05)
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]
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init = 200_000 # ARGV[0]
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n = Integer(init)
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offset_momentum(BODIES)
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puts "%.9f" % energy(BODIES)
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nbodies = BODIES.size
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dt = 0.01
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n.times do
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i = 0
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while i < nbodies
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b = BODIES[i]
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b.move_from_i(BODIES, nbodies, dt, i + 1)
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i += 1
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end
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end
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puts "%.9f" % energy(BODIES)
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