65 lines
1.3 KiB
Python
65 lines
1.3 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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# Contributed by Sebastien Loisel
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# Fixed by Isaac Gouy
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# Sped up by Josh Goldfoot
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# Dirtily sped up by Simon Descarpentries
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# Used list comprehension by Vadim Zelenin
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# 2to3
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from math import sqrt
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from sys import argv
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def eval_A(i, j):
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ij = i+j
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return 1.0 / (ij * (ij + 1) / 2 + i + 1)
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def eval_A_times_u(u):
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local_eval_A = eval_A
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return [ sum([ local_eval_A(i, j) * u_j
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for j, u_j in enumerate(u)
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]
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)
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for i in range(len(u))
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]
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def eval_At_times_u(u):
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local_eval_A = eval_A
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return [ sum([ local_eval_A(j, i) * u_j
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for j, u_j in enumerate(u)
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]
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)
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for i in range(len(u))
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]
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def eval_AtA_times_u(u):
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return eval_At_times_u(eval_A_times_u(u))
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def main():
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n = int(argv[1])
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u = [1] * n
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local_eval_AtA_times_u = eval_AtA_times_u
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for dummy in range(10):
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v = local_eval_AtA_times_u(u)
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u = local_eval_AtA_times_u(v)
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vBv = vv = 0
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for ue, ve in zip(u, v):
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vBv += ue * ve
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vv += ve * ve
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print("%0.9f" % (sqrt(vBv/vv)))
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main()
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