118 lines
3.4 KiB
Python
118 lines
3.4 KiB
Python
# The Computer Language Benchmarks Game
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# https://salsa.debian.org/benchmarksgame-team/benchmarksgame/
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#
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# originally by Kevin Carson
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# modified by Tupteq, Fredrik Johansson, and Daniel Nanz
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# modified by Maciej Fijalkowski
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# 2to3
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import sys
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def combinations(l):
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result = []
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for x in range(len(l) - 1):
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ls = l[x+1:]
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for y in ls:
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result.append((l[x],y))
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return result
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PI = 3.14159265358979323
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SOLAR_MASS = 4 * PI * PI
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DAYS_PER_YEAR = 365.24
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BODIES = {
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'sun': ([0.0, 0.0, 0.0], [0.0, 0.0, 0.0], SOLAR_MASS),
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'jupiter': ([4.84143144246472090e+00,
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-1.16032004402742839e+00,
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-1.03622044471123109e-01],
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[1.66007664274403694e-03 * DAYS_PER_YEAR,
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7.69901118419740425e-03 * DAYS_PER_YEAR,
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-6.90460016972063023e-05 * DAYS_PER_YEAR],
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9.54791938424326609e-04 * SOLAR_MASS),
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'saturn': ([8.34336671824457987e+00,
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4.12479856412430479e+00,
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-4.03523417114321381e-01],
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[-2.76742510726862411e-03 * DAYS_PER_YEAR,
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4.99852801234917238e-03 * DAYS_PER_YEAR,
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2.30417297573763929e-05 * DAYS_PER_YEAR],
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2.85885980666130812e-04 * SOLAR_MASS),
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'uranus': ([1.28943695621391310e+01,
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-1.51111514016986312e+01,
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-2.23307578892655734e-01],
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[2.96460137564761618e-03 * DAYS_PER_YEAR,
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2.37847173959480950e-03 * DAYS_PER_YEAR,
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-2.96589568540237556e-05 * DAYS_PER_YEAR],
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4.36624404335156298e-05 * SOLAR_MASS),
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'neptune': ([1.53796971148509165e+01,
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-2.59193146099879641e+01,
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1.79258772950371181e-01],
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[2.68067772490389322e-03 * DAYS_PER_YEAR,
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1.62824170038242295e-03 * DAYS_PER_YEAR,
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-9.51592254519715870e-05 * DAYS_PER_YEAR],
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5.15138902046611451e-05 * SOLAR_MASS) }
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SYSTEM = list(BODIES.values())
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PAIRS = combinations(SYSTEM)
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def advance(dt, n, bodies=SYSTEM, pairs=PAIRS):
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for i in range(n):
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for (([x1, y1, z1], v1, m1),
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([x2, y2, z2], v2, m2)) in pairs:
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dx = x1 - x2
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dy = y1 - y2
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dz = z1 - z2
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mag = dt * ((dx * dx + dy * dy + dz * dz) ** (-1.5))
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b1m = m1 * mag
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b2m = m2 * mag
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v1[0] -= dx * b2m
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v1[1] -= dy * b2m
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v1[2] -= dz * b2m
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v2[0] += dx * b1m
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v2[1] += dy * b1m
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v2[2] += dz * b1m
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for (r, [vx, vy, vz], m) in bodies:
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r[0] += dt * vx
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r[1] += dt * vy
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r[2] += dt * vz
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def report_energy(bodies=SYSTEM, pairs=PAIRS, e=0.0):
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for (((x1, y1, z1), v1, m1),
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((x2, y2, z2), v2, m2)) in pairs:
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dx = x1 - x2
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dy = y1 - y2
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dz = z1 - z2
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e -= (m1 * m2) / ((dx * dx + dy * dy + dz * dz) ** 0.5)
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for (r, [vx, vy, vz], m) in bodies:
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e += m * (vx * vx + vy * vy + vz * vz) / 2.
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print("%.9f" % e)
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def offset_momentum(ref, bodies=SYSTEM, px=0.0, py=0.0, pz=0.0):
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for (r, [vx, vy, vz], m) in bodies:
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px -= vx * m
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py -= vy * m
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pz -= vz * m
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(r, v, m) = ref
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v[0] = px / m
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v[1] = py / m
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v[2] = pz / m
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def main(n, ref='sun'):
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offset_momentum(BODIES[ref])
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report_energy()
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advance(0.01, n)
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report_energy()
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if __name__ == '__main__':
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main(int(sys.argv[1]))
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