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GH-100425: Note improved commutativity in sum(). by rhettinger · Pull Request #107785 · python/cpython · GitHub
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GH-100425: Note improved commutativity in sum().#107785

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rhettinger merged 1 commit into
python:mainfrom
rhettinger:sum_algo
Aug 8, 2023
Merged

GH-100425: Note improved commutativity in sum().#107785
rhettinger merged 1 commit into
python:mainfrom
rhettinger:sum_algo

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rhettinger commented Aug 8, 2023 •
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rhettinger added docs Documentation in the Doc dir skip news needs backport to 3.12 only security fixes labels Aug 8, 2023
bedevere-bot mentioned this pull request Aug 8, 2023
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rhettinger commented Aug 8, 2023

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Script to demonstrate the improvement:

from random import random from itertools import permutations n = 4 trials = 100 errors = 0 for i in range(trials): example = [random() for i in range(n)] if len(set(map(sum, permutations(example)))) != 1: errors += 1 print(i, sorted(example)) print(f'{errors / trials * 100.0=}%')

Formerly there was a 63% error rate. Now it is zero.

rhettinger merged commit aab6f71 into python:main Aug 8, 2023

miss-islington commented Aug 8, 2023

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Thanks @rhettinger for the PR 🌮🎉.. I'm working now to backport this PR to: 3.12.
🐍🍒⛏🤖

rhettinger deleted the sum_algo branch August 8, 2023 17:30

bedevere-bot commented Aug 8, 2023

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GH-107787 is a backport of this pull request to the 3.12 branch.

bedevere-bot removed the needs backport to 3.12 only security fixes label Aug 8, 2023
miss-islington pushed a commit to miss-islington/cpython that referenced this pull request Aug 8, 2023
pythonGH-100425: Note improved commutativity in sum(). (pythonGH-107785) …
adb32cd
(cherry picked from commit aab6f71) Co-authored-by: Raymond Hettinger <rhettinger@users.noreply.github.com>
enzbus mentioned this pull request Nov 10, 2023
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