#!/usr/bin/python

# The Computer Language Benchmarks Game

# http://shootout.alioth.debian.org/

#

# originally by Kevin Carson

# modified by Tupteq, Fredrik Johansson, and Daniel Nanz

# modified by Maciej Fijalkowski

# modified by HartsAntler for RPythonic

# 2to3

import datetime

import sys, math, time

if '..' not in sys.path: sys.path.append( '..' )

import rpythonic

rpy = rpythonic.RPython( 'testnbody', platform='linux' )

def combinations(l):

result = []

for x in range(len(l) - 1):

ls = l[x + 1:]

for y in ls:

result.append((l[x], y))

return result

PI = 3.14159265358979323

SOLAR_MASS = 4 * PI * PI

DAYS_PER_YEAR = 365.24

MASS = {

0: SOLAR_MASS, # sun

1: 9.54791938424326609e-04 * SOLAR_MASS, # jupiter

2: 2.85885980666130812e-04 * SOLAR_MASS, # saturn

3: 4.36624404335156298e-05 * SOLAR_MASS, # uranus

4: 5.15138902046611451e-05 * SOLAR_MASS # neptune

}

BODIES = {

'sun': ([0.0, 0.0, 0.0], [0.0, 0.0, 0.0], [0]),

'jupiter': ([4.84143144246472090e+00,

-1.16032004402742839e+00,

-1.03622044471123109e-01],

[1.66007664274403694e-03 * DAYS_PER_YEAR,

7.69901118419740425e-03 * DAYS_PER_YEAR,

-6.90460016972063023e-05 * DAYS_PER_YEAR]

, [1])

,

'saturn': ([8.34336671824457987e+00,

4.12479856412430479e+00,

-4.03523417114321381e-01],

[-2.76742510726862411e-03 * DAYS_PER_YEAR,

4.99852801234917238e-03 * DAYS_PER_YEAR,

2.30417297573763929e-05 * DAYS_PER_YEAR]

, [2]),

'uranus': ([1.28943695621391310e+01,

-1.51111514016986312e+01,

-2.23307578892655734e-01],

[2.96460137564761618e-03 * DAYS_PER_YEAR,

2.37847173959480950e-03 * DAYS_PER_YEAR,

-2.96589568540237556e-05 * DAYS_PER_YEAR],

[3]

),

'neptune': ([1.53796971148509165e+01,

-2.59193146099879641e+01,

1.79258772950371181e-01],

[2.68067772490389322e-03 * DAYS_PER_YEAR,

1.62824170038242295e-03 * DAYS_PER_YEAR,

-9.51592254519715870e-05 * DAYS_PER_YEAR],

[4]

) }

SYSTEM = list(BODIES.values())

PAIRS = combinations(SYSTEM)

def advance(dt, n, bodies, pairs):

for i in range(n):

for (([x1, y1, z1], v1, m1index),

([x2, y2, z2], v2, m2index)) in pairs:

m1 = MASS[m1index[0]]

m2 = MASS[m2index[0]]

dx = x1 - x2

dy = y1 - y2

dz = z1 - z2

#mag = dt * ((dx * dx + dy * dy + dz * dz) ** (-1.5))

mag = dt * math.pow((dx * dx + dy * dy + dz * dz), -1.5)

b1m = m1 * mag

b2m = m2 * mag

v1[0] -= dx * b2m

v1[1] -= dy * b2m

v1[2] -= dz * b2m

v2[0] += dx * b1m

v2[1] += dy * b1m

v2[2] += dz * b1m

for (r, [vx, vy, vz], mindex) in bodies:

m = MASS[mindex[0]]

r[0] += dt * vx

r[1] += dt * vy

r[2] += dt * vz

def report_energy(bodies, pairs, e):

for (((x1, y1, z1), v1, m1index),

((x2, y2, z2), v2, m2index)) in pairs:

m1 = MASS[m1index[0]]

m2 = MASS[m2index[0]]

dx = x1 - x2

dy = y1 - y2

dz = z1 - z2

e -= (m1 * m2) / math.pow((dx * dx + dy * dy + dz * dz), 0.5)

for (r, [vx, vy, vz], mindex) in bodies:

m = MASS[mindex[0]]

e += m * (vx * vx + vy * vy + vz * vz) / 2.

print("%s" % e)

def offset_momentum(ref, bodies, px, py, pz):

for (r, [vx, vy, vz], mindex) in bodies:

m = MASS[mindex[0]]

px -= vx * m

py -= vy * m

pz -= vz * m

(r, v, mindex) = ref

m = MASS[mindex[0]]

v[0] = px / m

v[1] = py / m

v[2] = pz / m

@rpy.standalone

def myentrypoint():

start = time.time()

n = 50000000

offset_momentum(BODIES['sun'], SYSTEM, 0.0, 0.0, 0.0)

report_energy(SYSTEM, PAIRS, 0.0)

advance(0.01, n, SYSTEM, PAIRS)

report_energy(SYSTEM, PAIRS, 0.0)

print( 'Took: ', time.time()-start )

#if __name__ == '__main__':

# t1 = datetime.datetime.now()

# main(int(sys.argv[1]))

# t2 = datetime.datetime.now()

# print "Took:", t2 - t1

pak = rpy.compile()

pak.test()

pak.save( './nbody_rpythonic' )