mirror of https://github.com/exaloop/codon.git
63 lines
1.5 KiB
Python
63 lines
1.5 KiB
Python
"""
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MathWorld: "Hundred-Dollar, Hundred-Digit Challenge Problems", Challenge #3.
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http://mathworld.wolfram.com/Hundred-DollarHundred-DigitChallengeProblems.html
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The Computer Language Benchmarks Game
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http://benchmarksgame.alioth.debian.org/u64q/spectralnorm-description.html#spectralnorm
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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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Concurrency by Jason Stitt
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Adapted for Codon by @arshajii
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"""
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from time import time
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DEFAULT_N = 260
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def eval_A(i, j):
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return 1.0 / ((i + j) * (i + j + 1) // 2 + i + 1)
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def eval_times_u(func, u):
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return [func((i, u)) for i in range(len(list(u)))]
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def part_At_times_u(i_u):
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i, u = i_u
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partial_sum = 0.
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for j, u_j in enumerate(u):
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partial_sum += eval_A(j, i) * u_j
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return partial_sum
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def part_A_times_u(i_u):
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i, u = i_u
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partial_sum = 0.
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for j, u_j in enumerate(u):
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partial_sum += eval_A(i, j) * u_j
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return partial_sum
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def eval_AtA_times_u(u):
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return eval_times_u(part_At_times_u, eval_times_u(part_A_times_u, u))
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def bench_spectral_norm(loops):
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range_it = range(loops)
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total = 0.
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for _ in range_it:
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u = [1.] * DEFAULT_N
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v = None
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for dummy in range(10):
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v = eval_AtA_times_u(u)
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u = 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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total += vBv + vv
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return total
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t0 = time()
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print(bench_spectral_norm(100))
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t1 = time()
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print(t1 - t0)
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